Skip to main content

core/num/
f32.rs

1//! Constants for the `f32` single-precision floating point type.
2//!
3//! *[See also the `f32` primitive type][f32].*
4//!
5//! Mathematically significant numbers are provided in the `consts` sub-module.
6//!
7//! For the constants defined directly in this module
8//! (as distinct from those defined in the `consts` sub-module),
9//! new code should instead use the associated constants
10//! defined directly on the `f32` type.
11
12#![stable(feature = "rust1", since = "1.0.0")]
13
14use crate::convert::FloatToInt;
15use crate::num::FpCategory;
16use crate::panic::const_assert;
17use crate::{cfg_select, intrinsics, mem};
18
19/// The radix or base of the internal representation of `f32`.
20/// Use [`f32::RADIX`] instead.
21///
22/// # Examples
23///
24/// ```rust
25/// // deprecated way
26/// # #[allow(deprecated, deprecated_in_future)]
27/// let r = std::f32::RADIX;
28///
29/// // intended way
30/// let r = f32::RADIX;
31/// ```
32#[stable(feature = "rust1", since = "1.0.0")]
33#[deprecated(since = "TBD", note = "replaced by the `RADIX` associated constant on `f32`")]
34#[rustc_diagnostic_item = "f32_legacy_const_radix"]
35pub const RADIX: u32 = f32::RADIX;
36
37/// Number of significant digits in base 2.
38/// Use [`f32::MANTISSA_DIGITS`] instead.
39///
40/// # Examples
41///
42/// ```rust
43/// // deprecated way
44/// # #[allow(deprecated, deprecated_in_future)]
45/// let d = std::f32::MANTISSA_DIGITS;
46///
47/// // intended way
48/// let d = f32::MANTISSA_DIGITS;
49/// ```
50#[stable(feature = "rust1", since = "1.0.0")]
51#[deprecated(
52    since = "TBD",
53    note = "replaced by the `MANTISSA_DIGITS` associated constant on `f32`"
54)]
55#[rustc_diagnostic_item = "f32_legacy_const_mantissa_dig"]
56pub const MANTISSA_DIGITS: u32 = f32::MANTISSA_DIGITS;
57
58/// Approximate number of significant digits in base 10.
59/// Use [`f32::DIGITS`] instead.
60///
61/// # Examples
62///
63/// ```rust
64/// // deprecated way
65/// # #[allow(deprecated, deprecated_in_future)]
66/// let d = std::f32::DIGITS;
67///
68/// // intended way
69/// let d = f32::DIGITS;
70/// ```
71#[stable(feature = "rust1", since = "1.0.0")]
72#[deprecated(since = "TBD", note = "replaced by the `DIGITS` associated constant on `f32`")]
73#[rustc_diagnostic_item = "f32_legacy_const_digits"]
74pub const DIGITS: u32 = f32::DIGITS;
75
76/// [Machine epsilon] value for `f32`.
77/// Use [`f32::EPSILON`] instead.
78///
79/// This is the difference between `1.0` and the next larger representable number.
80///
81/// [Machine epsilon]: https://en.wikipedia.org/wiki/Machine_epsilon
82///
83/// # Examples
84///
85/// ```rust
86/// // deprecated way
87/// # #[allow(deprecated, deprecated_in_future)]
88/// let e = std::f32::EPSILON;
89///
90/// // intended way
91/// let e = f32::EPSILON;
92/// ```
93#[stable(feature = "rust1", since = "1.0.0")]
94#[deprecated(since = "TBD", note = "replaced by the `EPSILON` associated constant on `f32`")]
95#[rustc_diagnostic_item = "f32_legacy_const_epsilon"]
96pub const EPSILON: f32 = f32::EPSILON;
97
98/// Smallest finite `f32` value.
99/// Use [`f32::MIN`] instead.
100///
101/// # Examples
102///
103/// ```rust
104/// // deprecated way
105/// # #[allow(deprecated, deprecated_in_future)]
106/// let min = std::f32::MIN;
107///
108/// // intended way
109/// let min = f32::MIN;
110/// ```
111#[stable(feature = "rust1", since = "1.0.0")]
112#[deprecated(since = "TBD", note = "replaced by the `MIN` associated constant on `f32`")]
113#[rustc_diagnostic_item = "f32_legacy_const_min"]
114pub const MIN: f32 = f32::MIN;
115
116/// Smallest positive normal `f32` value.
117/// Use [`f32::MIN_POSITIVE`] instead.
118///
119/// # Examples
120///
121/// ```rust
122/// // deprecated way
123/// # #[allow(deprecated, deprecated_in_future)]
124/// let min = std::f32::MIN_POSITIVE;
125///
126/// // intended way
127/// let min = f32::MIN_POSITIVE;
128/// ```
129#[stable(feature = "rust1", since = "1.0.0")]
130#[deprecated(since = "TBD", note = "replaced by the `MIN_POSITIVE` associated constant on `f32`")]
131#[rustc_diagnostic_item = "f32_legacy_const_min_positive"]
132pub const MIN_POSITIVE: f32 = f32::MIN_POSITIVE;
133
134/// Largest finite `f32` value.
135/// Use [`f32::MAX`] instead.
136///
137/// # Examples
138///
139/// ```rust
140/// // deprecated way
141/// # #[allow(deprecated, deprecated_in_future)]
142/// let max = std::f32::MAX;
143///
144/// // intended way
145/// let max = f32::MAX;
146/// ```
147#[stable(feature = "rust1", since = "1.0.0")]
148#[deprecated(since = "TBD", note = "replaced by the `MAX` associated constant on `f32`")]
149#[rustc_diagnostic_item = "f32_legacy_const_max"]
150pub const MAX: f32 = f32::MAX;
151
152/// One greater than the minimum possible normal power of 2 exponent.
153/// Use [`f32::MIN_EXP`] instead.
154///
155/// # Examples
156///
157/// ```rust
158/// // deprecated way
159/// # #[allow(deprecated, deprecated_in_future)]
160/// let min = std::f32::MIN_EXP;
161///
162/// // intended way
163/// let min = f32::MIN_EXP;
164/// ```
165#[stable(feature = "rust1", since = "1.0.0")]
166#[deprecated(since = "TBD", note = "replaced by the `MIN_EXP` associated constant on `f32`")]
167#[rustc_diagnostic_item = "f32_legacy_const_min_exp"]
168pub const MIN_EXP: i32 = f32::MIN_EXP;
169
170/// Maximum possible power of 2 exponent.
171/// Use [`f32::MAX_EXP`] instead.
172///
173/// # Examples
174///
175/// ```rust
176/// // deprecated way
177/// # #[allow(deprecated, deprecated_in_future)]
178/// let max = std::f32::MAX_EXP;
179///
180/// // intended way
181/// let max = f32::MAX_EXP;
182/// ```
183#[stable(feature = "rust1", since = "1.0.0")]
184#[deprecated(since = "TBD", note = "replaced by the `MAX_EXP` associated constant on `f32`")]
185#[rustc_diagnostic_item = "f32_legacy_const_max_exp"]
186pub const MAX_EXP: i32 = f32::MAX_EXP;
187
188/// Minimum possible normal power of 10 exponent.
189/// Use [`f32::MIN_10_EXP`] instead.
190///
191/// # Examples
192///
193/// ```rust
194/// // deprecated way
195/// # #[allow(deprecated, deprecated_in_future)]
196/// let min = std::f32::MIN_10_EXP;
197///
198/// // intended way
199/// let min = f32::MIN_10_EXP;
200/// ```
201#[stable(feature = "rust1", since = "1.0.0")]
202#[deprecated(since = "TBD", note = "replaced by the `MIN_10_EXP` associated constant on `f32`")]
203#[rustc_diagnostic_item = "f32_legacy_const_min_10_exp"]
204pub const MIN_10_EXP: i32 = f32::MIN_10_EXP;
205
206/// Maximum possible power of 10 exponent.
207/// Use [`f32::MAX_10_EXP`] instead.
208///
209/// # Examples
210///
211/// ```rust
212/// // deprecated way
213/// # #[allow(deprecated, deprecated_in_future)]
214/// let max = std::f32::MAX_10_EXP;
215///
216/// // intended way
217/// let max = f32::MAX_10_EXP;
218/// ```
219#[stable(feature = "rust1", since = "1.0.0")]
220#[deprecated(since = "TBD", note = "replaced by the `MAX_10_EXP` associated constant on `f32`")]
221#[rustc_diagnostic_item = "f32_legacy_const_max_10_exp"]
222pub const MAX_10_EXP: i32 = f32::MAX_10_EXP;
223
224/// Not a Number (NaN).
225/// Use [`f32::NAN`] instead.
226///
227/// # Examples
228///
229/// ```rust
230/// // deprecated way
231/// # #[allow(deprecated, deprecated_in_future)]
232/// let nan = std::f32::NAN;
233///
234/// // intended way
235/// let nan = f32::NAN;
236/// ```
237#[stable(feature = "rust1", since = "1.0.0")]
238#[deprecated(since = "TBD", note = "replaced by the `NAN` associated constant on `f32`")]
239#[rustc_diagnostic_item = "f32_legacy_const_nan"]
240pub const NAN: f32 = f32::NAN;
241
242/// Infinity (∞).
243/// Use [`f32::INFINITY`] instead.
244///
245/// # Examples
246///
247/// ```rust
248/// // deprecated way
249/// # #[allow(deprecated, deprecated_in_future)]
250/// let inf = std::f32::INFINITY;
251///
252/// // intended way
253/// let inf = f32::INFINITY;
254/// ```
255#[stable(feature = "rust1", since = "1.0.0")]
256#[deprecated(since = "TBD", note = "replaced by the `INFINITY` associated constant on `f32`")]
257#[rustc_diagnostic_item = "f32_legacy_const_infinity"]
258pub const INFINITY: f32 = f32::INFINITY;
259
260/// Negative infinity (−∞).
261/// Use [`f32::NEG_INFINITY`] instead.
262///
263/// # Examples
264///
265/// ```rust
266/// // deprecated way
267/// # #[allow(deprecated, deprecated_in_future)]
268/// let ninf = std::f32::NEG_INFINITY;
269///
270/// // intended way
271/// let ninf = f32::NEG_INFINITY;
272/// ```
273#[stable(feature = "rust1", since = "1.0.0")]
274#[deprecated(since = "TBD", note = "replaced by the `NEG_INFINITY` associated constant on `f32`")]
275#[rustc_diagnostic_item = "f32_legacy_const_neg_infinity"]
276pub const NEG_INFINITY: f32 = f32::NEG_INFINITY;
277
278/// Basic mathematical constants.
279#[stable(feature = "rust1", since = "1.0.0")]
280#[rustc_diagnostic_item = "f32_consts_mod"]
281pub mod consts {
282    // FIXME: replace with mathematical constants from cmath.
283
284    /// Archimedes' constant (π)
285    #[stable(feature = "rust1", since = "1.0.0")]
286    pub const PI: f32 = 3.14159265358979323846264338327950288_f32;
287
288    /// The full circle constant (τ)
289    ///
290    /// Equal to 2π.
291    #[stable(feature = "tau_constant", since = "1.47.0")]
292    pub const TAU: f32 = 6.28318530717958647692528676655900577_f32;
293
294    /// The golden ratio (φ)
295    #[stable(feature = "euler_gamma_golden_ratio", since = "1.94.0")]
296    pub const GOLDEN_RATIO: f32 = 1.618033988749894848204586834365638118_f32;
297
298    /// The Euler-Mascheroni constant (γ)
299    #[stable(feature = "euler_gamma_golden_ratio", since = "1.94.0")]
300    pub const EULER_GAMMA: f32 = 0.577215664901532860606512090082402431_f32;
301
302    /// π/2
303    #[stable(feature = "rust1", since = "1.0.0")]
304    pub const FRAC_PI_2: f32 = 1.57079632679489661923132169163975144_f32;
305
306    /// π/3
307    #[stable(feature = "rust1", since = "1.0.0")]
308    pub const FRAC_PI_3: f32 = 1.04719755119659774615421446109316763_f32;
309
310    /// π/4
311    #[stable(feature = "rust1", since = "1.0.0")]
312    pub const FRAC_PI_4: f32 = 0.785398163397448309615660845819875721_f32;
313
314    /// π/6
315    #[stable(feature = "rust1", since = "1.0.0")]
316    pub const FRAC_PI_6: f32 = 0.52359877559829887307710723054658381_f32;
317
318    /// π/8
319    #[stable(feature = "rust1", since = "1.0.0")]
320    pub const FRAC_PI_8: f32 = 0.39269908169872415480783042290993786_f32;
321
322    /// 1/π
323    #[stable(feature = "rust1", since = "1.0.0")]
324    pub const FRAC_1_PI: f32 = 0.318309886183790671537767526745028724_f32;
325
326    /// 1/sqrt(π)
327    #[unstable(feature = "more_float_constants", issue = "146939")]
328    pub const FRAC_1_SQRT_PI: f32 = 0.564189583547756286948079451560772586_f32;
329
330    /// 1/sqrt(2π)
331    #[doc(alias = "FRAC_1_SQRT_TAU")]
332    #[unstable(feature = "more_float_constants", issue = "146939")]
333    pub const FRAC_1_SQRT_2PI: f32 = 0.398942280401432677939946059934381868_f32;
334
335    /// 2/π
336    #[stable(feature = "rust1", since = "1.0.0")]
337    pub const FRAC_2_PI: f32 = 0.636619772367581343075535053490057448_f32;
338
339    /// 2/sqrt(π)
340    #[stable(feature = "rust1", since = "1.0.0")]
341    pub const FRAC_2_SQRT_PI: f32 = 1.12837916709551257389615890312154517_f32;
342
343    /// sqrt(2)
344    #[stable(feature = "rust1", since = "1.0.0")]
345    pub const SQRT_2: f32 = 1.41421356237309504880168872420969808_f32;
346
347    /// 1/sqrt(2)
348    #[stable(feature = "rust1", since = "1.0.0")]
349    pub const FRAC_1_SQRT_2: f32 = 0.707106781186547524400844362104849039_f32;
350
351    /// sqrt(3)
352    #[unstable(feature = "more_float_constants", issue = "146939")]
353    pub const SQRT_3: f32 = 1.732050807568877293527446341505872367_f32;
354
355    /// 1/sqrt(3)
356    #[unstable(feature = "more_float_constants", issue = "146939")]
357    pub const FRAC_1_SQRT_3: f32 = 0.577350269189625764509148780501957456_f32;
358
359    /// sqrt(5)
360    #[unstable(feature = "more_float_constants", issue = "146939")]
361    pub const SQRT_5: f32 = 2.23606797749978969640917366873127623_f32;
362
363    /// 1/sqrt(5)
364    #[unstable(feature = "more_float_constants", issue = "146939")]
365    pub const FRAC_1_SQRT_5: f32 = 0.44721359549995793928183473374625524_f32;
366
367    /// Euler's number (e)
368    #[stable(feature = "rust1", since = "1.0.0")]
369    pub const E: f32 = 2.71828182845904523536028747135266250_f32;
370
371    /// log<sub>2</sub>(e)
372    #[stable(feature = "rust1", since = "1.0.0")]
373    pub const LOG2_E: f32 = 1.44269504088896340735992468100189214_f32;
374
375    /// log<sub>2</sub>(10)
376    #[stable(feature = "extra_log_consts", since = "1.43.0")]
377    pub const LOG2_10: f32 = 3.32192809488736234787031942948939018_f32;
378
379    /// log<sub>10</sub>(e)
380    #[stable(feature = "rust1", since = "1.0.0")]
381    pub const LOG10_E: f32 = 0.434294481903251827651128918916605082_f32;
382
383    /// log<sub>10</sub>(2)
384    #[stable(feature = "extra_log_consts", since = "1.43.0")]
385    pub const LOG10_2: f32 = 0.301029995663981195213738894724493027_f32;
386
387    /// ln(2)
388    #[stable(feature = "rust1", since = "1.0.0")]
389    pub const LN_2: f32 = 0.693147180559945309417232121458176568_f32;
390
391    /// ln(10)
392    #[stable(feature = "rust1", since = "1.0.0")]
393    pub const LN_10: f32 = 2.30258509299404568401799145468436421_f32;
394}
395
396impl f32 {
397    /// The radix or base of the internal representation of `f32`.
398    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
399    pub const RADIX: u32 = 2;
400
401    /// The size of this float type in bits.
402    #[unstable(feature = "float_bits_const", issue = "151073")]
403    pub const BITS: u32 = 32;
404
405    /// Number of significant digits in base 2.
406    ///
407    /// Note that the size of the mantissa in the bitwise representation is one
408    /// smaller than this since the leading 1 is not stored explicitly.
409    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
410    pub const MANTISSA_DIGITS: u32 = 24;
411
412    /// Approximate number of significant digits in base 10.
413    ///
414    /// This is the maximum <i>x</i> such that any decimal number with <i>x</i>
415    /// significant digits can be converted to `f32` and back without loss.
416    ///
417    /// Equal to floor(log<sub>10</sub>&nbsp;2<sup>[`MANTISSA_DIGITS`]&nbsp;&minus;&nbsp;1</sup>).
418    ///
419    /// [`MANTISSA_DIGITS`]: f32::MANTISSA_DIGITS
420    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
421    pub const DIGITS: u32 = 6;
422
423    /// [Machine epsilon] value for `f32`.
424    ///
425    /// This is the difference between `1.0` and the next larger representable number.
426    ///
427    /// Equal to 2<sup>1&nbsp;&minus;&nbsp;[`MANTISSA_DIGITS`]</sup>.
428    ///
429    /// [Machine epsilon]: https://en.wikipedia.org/wiki/Machine_epsilon
430    /// [`MANTISSA_DIGITS`]: f32::MANTISSA_DIGITS
431    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
432    #[rustc_diagnostic_item = "f32_epsilon"]
433    pub const EPSILON: f32 = 1.19209290e-07_f32;
434
435    /// Smallest finite `f32` value.
436    ///
437    /// Equal to &minus;[`MAX`].
438    ///
439    /// [`MAX`]: f32::MAX
440    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
441    pub const MIN: f32 = -3.40282347e+38_f32;
442    /// Smallest positive normal `f32` value.
443    ///
444    /// Equal to 2<sup>[`MIN_EXP`]&nbsp;&minus;&nbsp;1</sup>.
445    ///
446    /// [`MIN_EXP`]: f32::MIN_EXP
447    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
448    pub const MIN_POSITIVE: f32 = 1.17549435e-38_f32;
449    /// Largest finite `f32` value.
450    ///
451    /// Equal to
452    /// (1&nbsp;&minus;&nbsp;2<sup>&minus;[`MANTISSA_DIGITS`]</sup>)&nbsp;2<sup>[`MAX_EXP`]</sup>.
453    ///
454    /// [`MANTISSA_DIGITS`]: f32::MANTISSA_DIGITS
455    /// [`MAX_EXP`]: f32::MAX_EXP
456    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
457    pub const MAX: f32 = 3.40282347e+38_f32;
458
459    /// One greater than the minimum possible *normal* power of 2 exponent
460    /// for a significand bounded by 1 ≤ x < 2 (i.e. the IEEE definition).
461    ///
462    /// This corresponds to the exact minimum possible *normal* power of 2 exponent
463    /// for a significand bounded by 0.5 ≤ x < 1 (i.e. the C definition).
464    /// In other words, all normal numbers representable by this type are
465    /// greater than or equal to 0.5&nbsp;×&nbsp;2<sup><i>MIN_EXP</i></sup>.
466    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
467    pub const MIN_EXP: i32 = -125;
468    /// One greater than the maximum possible power of 2 exponent
469    /// for a significand bounded by 1 ≤ x < 2 (i.e. the IEEE definition).
470    ///
471    /// This corresponds to the exact maximum possible power of 2 exponent
472    /// for a significand bounded by 0.5 ≤ x < 1 (i.e. the C definition).
473    /// In other words, all numbers representable by this type are
474    /// strictly less than 2<sup><i>MAX_EXP</i></sup>.
475    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
476    pub const MAX_EXP: i32 = 128;
477
478    /// Minimum <i>x</i> for which 10<sup><i>x</i></sup> is normal.
479    ///
480    /// Equal to ceil(log<sub>10</sub>&nbsp;[`MIN_POSITIVE`]).
481    ///
482    /// [`MIN_POSITIVE`]: f32::MIN_POSITIVE
483    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
484    pub const MIN_10_EXP: i32 = -37;
485    /// Maximum <i>x</i> for which 10<sup><i>x</i></sup> is normal.
486    ///
487    /// Equal to floor(log<sub>10</sub>&nbsp;[`MAX`]).
488    ///
489    /// [`MAX`]: f32::MAX
490    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
491    pub const MAX_10_EXP: i32 = 38;
492
493    /// Not a Number (NaN).
494    ///
495    /// Note that IEEE 754 doesn't define just a single NaN value; a plethora of bit patterns are
496    /// considered to be NaN. Furthermore, the standard makes a difference between a "signaling" and
497    /// a "quiet" NaN, and allows inspecting its "payload" (the unspecified bits in the bit pattern)
498    /// and its sign. See the [specification of NaN bit patterns](f32#nan-bit-patterns) for more
499    /// info.
500    ///
501    /// This constant is guaranteed to be a quiet NaN (on targets that follow the Rust assumptions
502    /// that the quiet/signaling bit being set to 1 indicates a quiet NaN). Beyond that, nothing is
503    /// guaranteed about the specific bit pattern chosen here: both payload and sign are arbitrary.
504    /// The concrete bit pattern may change across Rust versions and target platforms.
505    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
506    #[rustc_diagnostic_item = "f32_nan"]
507    #[allow(clippy::eq_op)]
508    pub const NAN: f32 = 0.0_f32 / 0.0_f32;
509    /// Infinity (∞).
510    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
511    pub const INFINITY: f32 = 1.0_f32 / 0.0_f32;
512    /// Negative infinity (−∞).
513    #[stable(feature = "assoc_int_consts", since = "1.43.0")]
514    pub const NEG_INFINITY: f32 = -1.0_f32 / 0.0_f32;
515
516    /// Sign bit
517    pub(crate) const SIGN_MASK: u32 = 0x8000_0000;
518
519    /// Exponent mask
520    pub(crate) const EXP_MASK: u32 = 0x7f80_0000;
521
522    /// Mantissa mask
523    pub(crate) const MAN_MASK: u32 = 0x007f_ffff;
524
525    /// Minimum representable positive value (min subnormal)
526    const TINY_BITS: u32 = 0x1;
527
528    /// Minimum representable negative value (min negative subnormal)
529    const NEG_TINY_BITS: u32 = Self::TINY_BITS | Self::SIGN_MASK;
530
531    /// Returns `true` if this value is NaN.
532    ///
533    /// ```
534    /// let nan = f32::NAN;
535    /// let f = 7.0_f32;
536    ///
537    /// assert!(nan.is_nan());
538    /// assert!(!f.is_nan());
539    /// ```
540    #[must_use]
541    #[stable(feature = "rust1", since = "1.0.0")]
542    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
543    #[inline]
544    #[allow(clippy::eq_op)] // > if you intended to check if the operand is NaN, use `.is_nan()` instead :)
545    pub const fn is_nan(self) -> bool {
546        self != self
547    }
548
549    /// Returns `true` if this value is positive infinity or negative infinity, and
550    /// `false` otherwise.
551    ///
552    /// ```
553    /// let f = 7.0f32;
554    /// let inf = f32::INFINITY;
555    /// let neg_inf = f32::NEG_INFINITY;
556    /// let nan = f32::NAN;
557    ///
558    /// assert!(!f.is_infinite());
559    /// assert!(!nan.is_infinite());
560    ///
561    /// assert!(inf.is_infinite());
562    /// assert!(neg_inf.is_infinite());
563    /// ```
564    #[must_use]
565    #[stable(feature = "rust1", since = "1.0.0")]
566    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
567    #[inline]
568    pub const fn is_infinite(self) -> bool {
569        // Getting clever with transmutation can result in incorrect answers on some FPUs
570        // FIXME: alter the Rust <-> Rust calling convention to prevent this problem.
571        // See https://github.com/rust-lang/rust/issues/72327
572        (self == f32::INFINITY) | (self == f32::NEG_INFINITY)
573    }
574
575    /// Returns `true` if this number is neither infinite nor NaN.
576    ///
577    /// ```
578    /// let f = 7.0f32;
579    /// let inf = f32::INFINITY;
580    /// let neg_inf = f32::NEG_INFINITY;
581    /// let nan = f32::NAN;
582    ///
583    /// assert!(f.is_finite());
584    ///
585    /// assert!(!nan.is_finite());
586    /// assert!(!inf.is_finite());
587    /// assert!(!neg_inf.is_finite());
588    /// ```
589    #[must_use]
590    #[stable(feature = "rust1", since = "1.0.0")]
591    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
592    #[inline]
593    pub const fn is_finite(self) -> bool {
594        // There's no need to handle NaN separately: if self is NaN,
595        // the comparison is not true, exactly as desired.
596        self.abs() < Self::INFINITY
597    }
598
599    /// Returns `true` if the number is [subnormal].
600    ///
601    /// ```
602    /// let min = f32::MIN_POSITIVE; // 1.17549435e-38f32
603    /// let max = f32::MAX;
604    /// let lower_than_min = 1.0e-40_f32;
605    /// let zero = 0.0_f32;
606    ///
607    /// assert!(!min.is_subnormal());
608    /// assert!(!max.is_subnormal());
609    ///
610    /// assert!(!zero.is_subnormal());
611    /// assert!(!f32::NAN.is_subnormal());
612    /// assert!(!f32::INFINITY.is_subnormal());
613    /// // Values between `0` and `min` are Subnormal.
614    /// assert!(lower_than_min.is_subnormal());
615    /// ```
616    /// [subnormal]: https://en.wikipedia.org/wiki/Denormal_number
617    #[must_use]
618    #[stable(feature = "is_subnormal", since = "1.53.0")]
619    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
620    #[inline]
621    pub const fn is_subnormal(self) -> bool {
622        matches!(self.classify(), FpCategory::Subnormal)
623    }
624
625    /// Returns `true` if the number is neither zero, infinite,
626    /// [subnormal], or NaN.
627    ///
628    /// ```
629    /// let min = f32::MIN_POSITIVE; // 1.17549435e-38f32
630    /// let max = f32::MAX;
631    /// let lower_than_min = 1.0e-40_f32;
632    /// let zero = 0.0_f32;
633    ///
634    /// assert!(min.is_normal());
635    /// assert!(max.is_normal());
636    ///
637    /// assert!(!zero.is_normal());
638    /// assert!(!f32::NAN.is_normal());
639    /// assert!(!f32::INFINITY.is_normal());
640    /// // Values between `0` and `min` are Subnormal.
641    /// assert!(!lower_than_min.is_normal());
642    /// ```
643    /// [subnormal]: https://en.wikipedia.org/wiki/Denormal_number
644    #[must_use]
645    #[stable(feature = "rust1", since = "1.0.0")]
646    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
647    #[inline]
648    pub const fn is_normal(self) -> bool {
649        matches!(self.classify(), FpCategory::Normal)
650    }
651
652    /// Returns the floating point category of the number. If only one property
653    /// is going to be tested, it is generally faster to use the specific
654    /// predicate instead.
655    ///
656    /// ```
657    /// use std::num::FpCategory;
658    ///
659    /// let num = 12.4_f32;
660    /// let inf = f32::INFINITY;
661    ///
662    /// assert_eq!(num.classify(), FpCategory::Normal);
663    /// assert_eq!(inf.classify(), FpCategory::Infinite);
664    /// ```
665    #[stable(feature = "rust1", since = "1.0.0")]
666    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
667    pub const fn classify(self) -> FpCategory {
668        // We used to have complicated logic here that avoids the simple bit-based tests to work
669        // around buggy codegen for x87 targets (see
670        // https://github.com/rust-lang/rust/issues/114479). However, some LLVM versions later, none
671        // of our tests is able to find any difference between the complicated and the naive
672        // version, so now we are back to the naive version.
673        let b = self.to_bits();
674        match (b & Self::MAN_MASK, b & Self::EXP_MASK) {
675            (0, Self::EXP_MASK) => FpCategory::Infinite,
676            (_, Self::EXP_MASK) => FpCategory::Nan,
677            (0, 0) => FpCategory::Zero,
678            (_, 0) => FpCategory::Subnormal,
679            _ => FpCategory::Normal,
680        }
681    }
682
683    /// Returns `true` if `self` has a positive sign, including `+0.0`, NaNs with
684    /// positive sign bit and positive infinity.
685    ///
686    /// Note that IEEE 754 doesn't assign any meaning to the sign bit in case of
687    /// a NaN, and as Rust doesn't guarantee that the bit pattern of NaNs are
688    /// conserved over arithmetic operations, the result of `is_sign_positive` on
689    /// a NaN might produce an unexpected or non-portable result. See the [specification
690    /// of NaN bit patterns](f32#nan-bit-patterns) for more info. Use `self.signum() == 1.0`
691    /// if you need fully portable behavior (will return `false` for all NaNs).
692    ///
693    /// ```
694    /// let f = 7.0_f32;
695    /// let g = -7.0_f32;
696    ///
697    /// assert!(f.is_sign_positive());
698    /// assert!(!g.is_sign_positive());
699    /// ```
700    #[must_use]
701    #[stable(feature = "rust1", since = "1.0.0")]
702    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
703    #[inline]
704    pub const fn is_sign_positive(self) -> bool {
705        !self.is_sign_negative()
706    }
707
708    /// Returns `true` if `self` has a negative sign, including `-0.0`, NaNs with
709    /// negative sign bit and negative infinity.
710    ///
711    /// Note that IEEE 754 doesn't assign any meaning to the sign bit in case of
712    /// a NaN, and as Rust doesn't guarantee that the bit pattern of NaNs are
713    /// conserved over arithmetic operations, the result of `is_sign_negative` on
714    /// a NaN might produce an unexpected or non-portable result. See the [specification
715    /// of NaN bit patterns](f32#nan-bit-patterns) for more info. Use `self.signum() == -1.0`
716    /// if you need fully portable behavior (will return `false` for all NaNs).
717    ///
718    /// ```
719    /// let f = 7.0f32;
720    /// let g = -7.0f32;
721    ///
722    /// assert!(!f.is_sign_negative());
723    /// assert!(g.is_sign_negative());
724    /// ```
725    #[must_use]
726    #[stable(feature = "rust1", since = "1.0.0")]
727    #[rustc_const_stable(feature = "const_float_classify", since = "1.83.0")]
728    #[inline]
729    pub const fn is_sign_negative(self) -> bool {
730        // IEEE754 says: isSignMinus(x) is true if and only if x has negative sign. isSignMinus
731        // applies to zeros and NaNs as well.
732        self.to_bits() & 0x8000_0000 != 0
733    }
734
735    /// Returns the least number greater than `self`.
736    ///
737    /// Let `TINY` be the smallest representable positive `f32`. Then,
738    ///  - if `self.is_nan()`, this returns `self`;
739    ///  - if `self` is [`NEG_INFINITY`], this returns [`MIN`];
740    ///  - if `self` is `-TINY`, this returns -0.0;
741    ///  - if `self` is -0.0 or +0.0, this returns `TINY`;
742    ///  - if `self` is [`MAX`] or [`INFINITY`], this returns [`INFINITY`];
743    ///  - otherwise the unique least value greater than `self` is returned.
744    ///
745    /// The identity `x.next_up() == -(-x).next_down()` holds for all non-NaN `x`. When `x`
746    /// is finite `x == x.next_up().next_down()` also holds.
747    ///
748    /// ```rust
749    /// // f32::EPSILON is the difference between 1.0 and the next number up.
750    /// assert_eq!(1.0f32.next_up(), 1.0 + f32::EPSILON);
751    /// // But not for most numbers.
752    /// assert!(0.1f32.next_up() < 0.1 + f32::EPSILON);
753    /// assert_eq!(16777216f32.next_up(), 16777218.0);
754    /// ```
755    ///
756    /// This operation corresponds to IEEE-754 `nextUp`.
757    ///
758    /// [`NEG_INFINITY`]: Self::NEG_INFINITY
759    /// [`INFINITY`]: Self::INFINITY
760    /// [`MIN`]: Self::MIN
761    /// [`MAX`]: Self::MAX
762    #[inline]
763    #[doc(alias = "nextUp")]
764    #[stable(feature = "float_next_up_down", since = "1.86.0")]
765    #[rustc_const_stable(feature = "float_next_up_down", since = "1.86.0")]
766    pub const fn next_up(self) -> Self {
767        // Some targets violate Rust's assumption of IEEE semantics, e.g. by flushing
768        // denormals to zero. This is in general unsound and unsupported, but here
769        // we do our best to still produce the correct result on such targets.
770        let bits = self.to_bits();
771        if self.is_nan() || bits == Self::INFINITY.to_bits() {
772            return self;
773        }
774
775        let abs = bits & !Self::SIGN_MASK;
776        let next_bits = if abs == 0 {
777            Self::TINY_BITS
778        } else if bits == abs {
779            bits + 1
780        } else {
781            bits - 1
782        };
783        Self::from_bits(next_bits)
784    }
785
786    /// Returns the greatest number less than `self`.
787    ///
788    /// Let `TINY` be the smallest representable positive `f32`. Then,
789    ///  - if `self.is_nan()`, this returns `self`;
790    ///  - if `self` is [`INFINITY`], this returns [`MAX`];
791    ///  - if `self` is `TINY`, this returns 0.0;
792    ///  - if `self` is -0.0 or +0.0, this returns `-TINY`;
793    ///  - if `self` is [`MIN`] or [`NEG_INFINITY`], this returns [`NEG_INFINITY`];
794    ///  - otherwise the unique greatest value less than `self` is returned.
795    ///
796    /// The identity `x.next_down() == -(-x).next_up()` holds for all non-NaN `x`. When `x`
797    /// is finite `x == x.next_down().next_up()` also holds.
798    ///
799    /// ```rust
800    /// let x = 1.0f32;
801    /// // Clamp value into range [0, 1).
802    /// let clamped = x.clamp(0.0, 1.0f32.next_down());
803    /// assert!(clamped < 1.0);
804    /// assert_eq!(clamped.next_up(), 1.0);
805    /// ```
806    ///
807    /// This operation corresponds to IEEE-754 `nextDown`.
808    ///
809    /// [`NEG_INFINITY`]: Self::NEG_INFINITY
810    /// [`INFINITY`]: Self::INFINITY
811    /// [`MIN`]: Self::MIN
812    /// [`MAX`]: Self::MAX
813    #[inline]
814    #[doc(alias = "nextDown")]
815    #[stable(feature = "float_next_up_down", since = "1.86.0")]
816    #[rustc_const_stable(feature = "float_next_up_down", since = "1.86.0")]
817    pub const fn next_down(self) -> Self {
818        // Some targets violate Rust's assumption of IEEE semantics, e.g. by flushing
819        // denormals to zero. This is in general unsound and unsupported, but here
820        // we do our best to still produce the correct result on such targets.
821        let bits = self.to_bits();
822        if self.is_nan() || bits == Self::NEG_INFINITY.to_bits() {
823            return self;
824        }
825
826        let abs = bits & !Self::SIGN_MASK;
827        let next_bits = if abs == 0 {
828            Self::NEG_TINY_BITS
829        } else if bits == abs {
830            bits - 1
831        } else {
832            bits + 1
833        };
834        Self::from_bits(next_bits)
835    }
836
837    /// Takes the reciprocal (inverse) of a number, `1/x`.
838    ///
839    /// ```
840    /// let x = 2.0_f32;
841    /// let abs_difference = (x.recip() - (1.0 / x)).abs();
842    ///
843    /// assert!(abs_difference <= f32::EPSILON);
844    /// ```
845    #[must_use = "this returns the result of the operation, without modifying the original"]
846    #[stable(feature = "rust1", since = "1.0.0")]
847    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
848    #[inline]
849    pub const fn recip(self) -> f32 {
850        1.0 / self
851    }
852
853    /// Converts radians to degrees.
854    ///
855    /// # Unspecified precision
856    ///
857    /// The precision of this function is non-deterministic. This means it varies by platform,
858    /// Rust version, and can even differ within the same execution from one invocation to the next.
859    ///
860    /// # Examples
861    ///
862    /// ```
863    /// let angle = std::f32::consts::PI;
864    ///
865    /// let abs_difference = (angle.to_degrees() - 180.0).abs();
866    /// # #[cfg(any(not(target_arch = "x86"), target_feature = "sse2"))]
867    /// assert!(abs_difference <= f32::EPSILON);
868    /// ```
869    #[must_use = "this returns the result of the operation, \
870                  without modifying the original"]
871    #[stable(feature = "f32_deg_rad_conversions", since = "1.7.0")]
872    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
873    #[inline]
874    pub const fn to_degrees(self) -> f32 {
875        // Use a literal to avoid double rounding, consts::PI is already rounded,
876        // and dividing would round again.
877        const PIS_IN_180: f32 = 57.2957795130823208767981548141051703_f32;
878        self * PIS_IN_180
879    }
880
881    /// Converts degrees to radians.
882    ///
883    /// # Unspecified precision
884    ///
885    /// The precision of this function is non-deterministic. This means it varies by platform,
886    /// Rust version, and can even differ within the same execution from one invocation to the next.
887    ///
888    /// # Examples
889    ///
890    /// ```
891    /// let angle = 180.0f32;
892    ///
893    /// let abs_difference = (angle.to_radians() - std::f32::consts::PI).abs();
894    ///
895    /// assert!(abs_difference <= f32::EPSILON);
896    /// ```
897    #[must_use = "this returns the result of the operation, \
898                  without modifying the original"]
899    #[stable(feature = "f32_deg_rad_conversions", since = "1.7.0")]
900    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
901    #[inline]
902    pub const fn to_radians(self) -> f32 {
903        // The division here is correctly rounded with respect to the true value of π/180.
904        // Although π is irrational and already rounded, the double rounding happens
905        // to produce correct result for f32.
906        const RADS_PER_DEG: f32 = consts::PI / 180.0;
907        self * RADS_PER_DEG
908    }
909
910    /// Returns the maximum of the two numbers, ignoring NaN.
911    ///
912    /// If exactly one of the arguments is NaN (quiet or signaling), then the other argument is
913    /// returned. If both arguments are NaN, the return value is NaN, with the bit pattern picked
914    /// using the usual [rules for arithmetic operations](f32#nan-bit-patterns). If the inputs
915    /// compare equal (such as for the case of `+0.0` and `-0.0`), either input may be returned
916    /// non-deterministically.
917    ///
918    /// The handling of NaNs follows the IEEE 754-2019 semantics for `maximumNumber`, treating all
919    /// NaNs the same way to ensure the operation is associative. The handling of signed zeros
920    /// follows the IEEE 754-2008 semantics for `maxNum`.
921    ///
922    /// ```
923    /// let x = 1.0f32;
924    /// let y = 2.0f32;
925    ///
926    /// assert_eq!(x.max(y), y);
927    /// assert_eq!(x.max(f32::NAN), x);
928    /// ```
929    #[must_use = "this returns the result of the comparison, without modifying either input"]
930    #[stable(feature = "rust1", since = "1.0.0")]
931    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
932    #[inline]
933    pub const fn max(self, other: f32) -> f32 {
934        intrinsics::maxnumf32(self, other)
935    }
936
937    /// Returns the minimum of the two numbers, ignoring NaN.
938    ///
939    /// If exactly one of the arguments is NaN (quiet or signaling), then the other argument is
940    /// returned. If both arguments are NaN, the return value is NaN, with the bit pattern picked
941    /// using the usual [rules for arithmetic operations](f32#nan-bit-patterns). If the inputs
942    /// compare equal (such as for the case of `+0.0` and `-0.0`), either input may be returned
943    /// non-deterministically.
944    ///
945    /// The handling of NaNs follows the IEEE 754-2019 semantics for `minimumNumber`, treating all
946    /// NaNs the same way to ensure the operation is associative. The handling of signed zeros
947    /// follows the IEEE 754-2008 semantics for `minNum`.
948    ///
949    /// ```
950    /// let x = 1.0f32;
951    /// let y = 2.0f32;
952    ///
953    /// assert_eq!(x.min(y), x);
954    /// assert_eq!(x.min(f32::NAN), x);
955    /// ```
956    #[must_use = "this returns the result of the comparison, without modifying either input"]
957    #[stable(feature = "rust1", since = "1.0.0")]
958    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
959    #[inline]
960    pub const fn min(self, other: f32) -> f32 {
961        intrinsics::minnumf32(self, other)
962    }
963
964    /// Returns the maximum of the two numbers, propagating NaN.
965    ///
966    /// If at least one of the arguments is NaN, the return value is NaN, with the bit pattern
967    /// picked using the usual [rules for arithmetic operations](f32#nan-bit-patterns). Furthermore,
968    /// `-0.0` is considered to be less than `+0.0`, making this function fully deterministic for
969    /// non-NaN inputs.
970    ///
971    /// This is in contrast to [`f32::max`] which only returns NaN when *both* arguments are NaN,
972    /// and which does not reliably order `-0.0` and `+0.0`.
973    ///
974    /// This follows the IEEE 754-2019 semantics for `maximum`.
975    ///
976    /// ```
977    /// #![feature(float_minimum_maximum)]
978    /// let x = 1.0f32;
979    /// let y = 2.0f32;
980    ///
981    /// assert_eq!(x.maximum(y), y);
982    /// assert!(x.maximum(f32::NAN).is_nan());
983    /// ```
984    #[must_use = "this returns the result of the comparison, without modifying either input"]
985    #[unstable(feature = "float_minimum_maximum", issue = "91079")]
986    #[inline]
987    pub const fn maximum(self, other: f32) -> f32 {
988        intrinsics::maximumf32(self, other)
989    }
990
991    /// Returns the minimum of the two numbers, propagating NaN.
992    ///
993    /// If at least one of the arguments is NaN, the return value is NaN, with the bit pattern
994    /// picked using the usual [rules for arithmetic operations](f32#nan-bit-patterns). Furthermore,
995    /// `-0.0` is considered to be less than `+0.0`, making this function fully deterministic for
996    /// non-NaN inputs.
997    ///
998    /// This is in contrast to [`f32::min`] which only returns NaN when *both* arguments are NaN,
999    /// and which does not reliably order `-0.0` and `+0.0`.
1000    ///
1001    /// This follows the IEEE 754-2019 semantics for `minimum`.
1002    ///
1003    /// ```
1004    /// #![feature(float_minimum_maximum)]
1005    /// let x = 1.0f32;
1006    /// let y = 2.0f32;
1007    ///
1008    /// assert_eq!(x.minimum(y), x);
1009    /// assert!(x.minimum(f32::NAN).is_nan());
1010    /// ```
1011    #[must_use = "this returns the result of the comparison, without modifying either input"]
1012    #[unstable(feature = "float_minimum_maximum", issue = "91079")]
1013    #[inline]
1014    pub const fn minimum(self, other: f32) -> f32 {
1015        intrinsics::minimumf32(self, other)
1016    }
1017
1018    /// Calculates the midpoint (average) between `self` and `rhs`.
1019    ///
1020    /// This returns NaN when *either* argument is NaN or if a combination of
1021    /// +inf and -inf is provided as arguments.
1022    ///
1023    /// # Examples
1024    ///
1025    /// ```
1026    /// assert_eq!(1f32.midpoint(4.0), 2.5);
1027    /// assert_eq!((-5.5f32).midpoint(8.0), 1.25);
1028    /// ```
1029    #[inline]
1030    #[doc(alias = "average")]
1031    #[stable(feature = "num_midpoint", since = "1.85.0")]
1032    #[rustc_const_stable(feature = "num_midpoint", since = "1.85.0")]
1033    pub const fn midpoint(self, other: f32) -> f32 {
1034        cfg_select! {
1035            // Allow faster implementation that have known good 64-bit float
1036            // implementations. Falling back to the branchy code on targets that don't
1037            // have 64-bit hardware floats or buggy implementations.
1038            // https://github.com/rust-lang/rust/pull/121062#issuecomment-2123408114
1039            any(
1040                target_arch = "x86_64",
1041                target_arch = "aarch64",
1042                all(any(target_arch = "riscv32", target_arch = "riscv64"), target_feature = "d"),
1043                all(target_arch = "loongarch64", target_feature = "d"),
1044                all(target_arch = "arm", target_feature = "vfp2"),
1045                target_arch = "wasm32",
1046                target_arch = "wasm64",
1047            ) => {
1048                ((self as f64 + other as f64) / 2.0) as f32
1049            }
1050            _ => {
1051                const HI: f32 = f32::MAX / 2.;
1052
1053                let (a, b) = (self, other);
1054                let abs_a = a.abs();
1055                let abs_b = b.abs();
1056
1057                if abs_a <= HI && abs_b <= HI {
1058                    // Overflow is impossible
1059                    (a + b) / 2.
1060                } else {
1061                    (a / 2.) + (b / 2.)
1062                }
1063            }
1064        }
1065    }
1066
1067    /// Rounds toward zero and converts to any primitive integer type,
1068    /// assuming that the value is finite and fits in that type.
1069    ///
1070    /// ```
1071    /// let value = 4.6_f32;
1072    /// let rounded = unsafe { value.to_int_unchecked::<u16>() };
1073    /// assert_eq!(rounded, 4);
1074    ///
1075    /// let value = -128.9_f32;
1076    /// let rounded = unsafe { value.to_int_unchecked::<i8>() };
1077    /// assert_eq!(rounded, i8::MIN);
1078    /// ```
1079    ///
1080    /// # Safety
1081    ///
1082    /// The value must:
1083    ///
1084    /// * Not be `NaN`
1085    /// * Not be infinite
1086    /// * Be representable in the return type `Int`, after truncating off its fractional part
1087    #[must_use = "this returns the result of the operation, \
1088                  without modifying the original"]
1089    #[stable(feature = "float_approx_unchecked_to", since = "1.44.0")]
1090    #[inline]
1091    pub unsafe fn to_int_unchecked<Int>(self) -> Int
1092    where
1093        Self: FloatToInt<Int>,
1094    {
1095        // SAFETY: the caller must uphold the safety contract for
1096        // `FloatToInt::to_int_unchecked`.
1097        unsafe { FloatToInt::<Int>::to_int_unchecked(self) }
1098    }
1099
1100    /// Raw transmutation to `u32`.
1101    ///
1102    /// This is currently identical to `transmute::<f32, u32>(self)` on all platforms.
1103    ///
1104    /// See [`from_bits`](Self::from_bits) for some discussion of the
1105    /// portability of this operation (there are almost no issues).
1106    ///
1107    /// Note that this function is distinct from `as` casting, which attempts to
1108    /// preserve the *numeric* value, and not the bitwise value.
1109    ///
1110    /// # Examples
1111    ///
1112    /// ```
1113    /// assert_ne!((1f32).to_bits(), 1f32 as u32); // to_bits() is not casting!
1114    /// assert_eq!((12.5f32).to_bits(), 0x41480000);
1115    ///
1116    /// ```
1117    #[must_use = "this returns the result of the operation, \
1118                  without modifying the original"]
1119    #[stable(feature = "float_bits_conv", since = "1.20.0")]
1120    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1121    #[inline]
1122    #[allow(unnecessary_transmutes)]
1123    pub const fn to_bits(self) -> u32 {
1124        // SAFETY: `u32` is a plain old datatype so we can always transmute to it.
1125        unsafe { mem::transmute(self) }
1126    }
1127
1128    /// Raw transmutation from `u32`.
1129    ///
1130    /// This is currently identical to `transmute::<u32, f32>(v)` on all platforms.
1131    /// It turns out this is incredibly portable, for two reasons:
1132    ///
1133    /// * Floats and Ints have the same endianness on all supported platforms.
1134    /// * IEEE 754 very precisely specifies the bit layout of floats.
1135    ///
1136    /// However there is one caveat: prior to the 2008 version of IEEE 754, how
1137    /// to interpret the NaN signaling bit wasn't actually specified. Most platforms
1138    /// (notably x86 and ARM) picked the interpretation that was ultimately
1139    /// standardized in 2008, but some didn't (notably MIPS). As a result, all
1140    /// signaling NaNs on MIPS are quiet NaNs on x86, and vice-versa.
1141    ///
1142    /// Rather than trying to preserve signaling-ness cross-platform, this
1143    /// implementation favors preserving the exact bits. This means that
1144    /// any payloads encoded in NaNs will be preserved even if the result of
1145    /// this method is sent over the network from an x86 machine to a MIPS one.
1146    ///
1147    /// If the results of this method are only manipulated by the same
1148    /// architecture that produced them, then there is no portability concern.
1149    ///
1150    /// If the input isn't NaN, then there is no portability concern.
1151    ///
1152    /// If you don't care about signalingness (very likely), then there is no
1153    /// portability concern.
1154    ///
1155    /// Note that this function is distinct from `as` casting, which attempts to
1156    /// preserve the *numeric* value, and not the bitwise value.
1157    ///
1158    /// # Examples
1159    ///
1160    /// ```
1161    /// let v = f32::from_bits(0x41480000);
1162    /// assert_eq!(v, 12.5);
1163    /// ```
1164    #[stable(feature = "float_bits_conv", since = "1.20.0")]
1165    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1166    #[must_use]
1167    #[inline]
1168    #[allow(unnecessary_transmutes)]
1169    pub const fn from_bits(v: u32) -> Self {
1170        // It turns out the safety issues with sNaN were overblown! Hooray!
1171        // SAFETY: `u32` is a plain old datatype so we can always transmute from it.
1172        unsafe { mem::transmute(v) }
1173    }
1174
1175    /// Returns the memory representation of this floating point number as a byte array in
1176    /// big-endian (network) byte order.
1177    ///
1178    /// See [`from_bits`](Self::from_bits) for some discussion of the
1179    /// portability of this operation (there are almost no issues).
1180    ///
1181    /// # Examples
1182    ///
1183    /// ```
1184    /// let bytes = 12.5f32.to_be_bytes();
1185    /// assert_eq!(bytes, [0x41, 0x48, 0x00, 0x00]);
1186    /// ```
1187    #[must_use = "this returns the result of the operation, \
1188                  without modifying the original"]
1189    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1190    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1191    #[inline]
1192    pub const fn to_be_bytes(self) -> [u8; 4] {
1193        self.to_bits().to_be_bytes()
1194    }
1195
1196    /// Returns the memory representation of this floating point number as a byte array in
1197    /// little-endian byte order.
1198    ///
1199    /// See [`from_bits`](Self::from_bits) for some discussion of the
1200    /// portability of this operation (there are almost no issues).
1201    ///
1202    /// # Examples
1203    ///
1204    /// ```
1205    /// let bytes = 12.5f32.to_le_bytes();
1206    /// assert_eq!(bytes, [0x00, 0x00, 0x48, 0x41]);
1207    /// ```
1208    #[must_use = "this returns the result of the operation, \
1209                  without modifying the original"]
1210    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1211    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1212    #[inline]
1213    pub const fn to_le_bytes(self) -> [u8; 4] {
1214        self.to_bits().to_le_bytes()
1215    }
1216
1217    /// Returns the memory representation of this floating point number as a byte array in
1218    /// native byte order.
1219    ///
1220    /// As the target platform's native endianness is used, portable code
1221    /// should use [`to_be_bytes`] or [`to_le_bytes`], as appropriate, instead.
1222    ///
1223    /// [`to_be_bytes`]: f32::to_be_bytes
1224    /// [`to_le_bytes`]: f32::to_le_bytes
1225    ///
1226    /// See [`from_bits`](Self::from_bits) for some discussion of the
1227    /// portability of this operation (there are almost no issues).
1228    ///
1229    /// # Examples
1230    ///
1231    /// ```
1232    /// let bytes = 12.5f32.to_ne_bytes();
1233    /// assert_eq!(
1234    ///     bytes,
1235    ///     if cfg!(target_endian = "big") {
1236    ///         [0x41, 0x48, 0x00, 0x00]
1237    ///     } else {
1238    ///         [0x00, 0x00, 0x48, 0x41]
1239    ///     }
1240    /// );
1241    /// ```
1242    #[must_use = "this returns the result of the operation, \
1243                  without modifying the original"]
1244    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1245    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1246    #[inline]
1247    pub const fn to_ne_bytes(self) -> [u8; 4] {
1248        self.to_bits().to_ne_bytes()
1249    }
1250
1251    /// Creates a floating point value from its representation as a byte array in big endian.
1252    ///
1253    /// See [`from_bits`](Self::from_bits) for some discussion of the
1254    /// portability of this operation (there are almost no issues).
1255    ///
1256    /// # Examples
1257    ///
1258    /// ```
1259    /// let value = f32::from_be_bytes([0x41, 0x48, 0x00, 0x00]);
1260    /// assert_eq!(value, 12.5);
1261    /// ```
1262    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1263    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1264    #[must_use]
1265    #[inline]
1266    pub const fn from_be_bytes(bytes: [u8; 4]) -> Self {
1267        Self::from_bits(u32::from_be_bytes(bytes))
1268    }
1269
1270    /// Creates a floating point value from its representation as a byte array in little endian.
1271    ///
1272    /// See [`from_bits`](Self::from_bits) for some discussion of the
1273    /// portability of this operation (there are almost no issues).
1274    ///
1275    /// # Examples
1276    ///
1277    /// ```
1278    /// let value = f32::from_le_bytes([0x00, 0x00, 0x48, 0x41]);
1279    /// assert_eq!(value, 12.5);
1280    /// ```
1281    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1282    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1283    #[must_use]
1284    #[inline]
1285    pub const fn from_le_bytes(bytes: [u8; 4]) -> Self {
1286        Self::from_bits(u32::from_le_bytes(bytes))
1287    }
1288
1289    /// Creates a floating point value from its representation as a byte array in native endian.
1290    ///
1291    /// As the target platform's native endianness is used, portable code
1292    /// likely wants to use [`from_be_bytes`] or [`from_le_bytes`], as
1293    /// appropriate instead.
1294    ///
1295    /// [`from_be_bytes`]: f32::from_be_bytes
1296    /// [`from_le_bytes`]: f32::from_le_bytes
1297    ///
1298    /// See [`from_bits`](Self::from_bits) for some discussion of the
1299    /// portability of this operation (there are almost no issues).
1300    ///
1301    /// # Examples
1302    ///
1303    /// ```
1304    /// let value = f32::from_ne_bytes(if cfg!(target_endian = "big") {
1305    ///     [0x41, 0x48, 0x00, 0x00]
1306    /// } else {
1307    ///     [0x00, 0x00, 0x48, 0x41]
1308    /// });
1309    /// assert_eq!(value, 12.5);
1310    /// ```
1311    #[stable(feature = "float_to_from_bytes", since = "1.40.0")]
1312    #[rustc_const_stable(feature = "const_float_bits_conv", since = "1.83.0")]
1313    #[must_use]
1314    #[inline]
1315    pub const fn from_ne_bytes(bytes: [u8; 4]) -> Self {
1316        Self::from_bits(u32::from_ne_bytes(bytes))
1317    }
1318
1319    /// Returns the ordering between `self` and `other`.
1320    ///
1321    /// Unlike the standard partial comparison between floating point numbers,
1322    /// this comparison always produces an ordering in accordance to
1323    /// the `totalOrder` predicate as defined in the IEEE 754 (2008 revision)
1324    /// floating point standard. The values are ordered in the following sequence:
1325    ///
1326    /// - negative quiet NaN
1327    /// - negative signaling NaN
1328    /// - negative infinity
1329    /// - negative numbers
1330    /// - negative subnormal numbers
1331    /// - negative zero
1332    /// - positive zero
1333    /// - positive subnormal numbers
1334    /// - positive numbers
1335    /// - positive infinity
1336    /// - positive signaling NaN
1337    /// - positive quiet NaN.
1338    ///
1339    /// The ordering established by this function does not always agree with the
1340    /// [`PartialOrd`] and [`PartialEq`] implementations of `f32`. For example,
1341    /// they consider negative and positive zero equal, while `total_cmp`
1342    /// doesn't.
1343    ///
1344    /// The interpretation of the signaling NaN bit follows the definition in
1345    /// the IEEE 754 standard, which may not match the interpretation by some of
1346    /// the older, non-conformant (e.g. MIPS) hardware implementations.
1347    ///
1348    /// # Example
1349    ///
1350    /// ```
1351    /// struct GoodBoy {
1352    ///     name: String,
1353    ///     weight: f32,
1354    /// }
1355    ///
1356    /// let mut bois = vec![
1357    ///     GoodBoy { name: "Pucci".to_owned(), weight: 0.1 },
1358    ///     GoodBoy { name: "Woofer".to_owned(), weight: 99.0 },
1359    ///     GoodBoy { name: "Yapper".to_owned(), weight: 10.0 },
1360    ///     GoodBoy { name: "Chonk".to_owned(), weight: f32::INFINITY },
1361    ///     GoodBoy { name: "Abs. Unit".to_owned(), weight: f32::NAN },
1362    ///     GoodBoy { name: "Floaty".to_owned(), weight: -5.0 },
1363    /// ];
1364    ///
1365    /// bois.sort_by(|a, b| a.weight.total_cmp(&b.weight));
1366    ///
1367    /// // `f32::NAN` could be positive or negative, which will affect the sort order.
1368    /// if f32::NAN.is_sign_negative() {
1369    ///     assert!(bois.into_iter().map(|b| b.weight)
1370    ///         .zip([f32::NAN, -5.0, 0.1, 10.0, 99.0, f32::INFINITY].iter())
1371    ///         .all(|(a, b)| a.to_bits() == b.to_bits()))
1372    /// } else {
1373    ///     assert!(bois.into_iter().map(|b| b.weight)
1374    ///         .zip([-5.0, 0.1, 10.0, 99.0, f32::INFINITY, f32::NAN].iter())
1375    ///         .all(|(a, b)| a.to_bits() == b.to_bits()))
1376    /// }
1377    /// ```
1378    #[stable(feature = "total_cmp", since = "1.62.0")]
1379    #[rustc_const_unstable(feature = "const_cmp", issue = "143800")]
1380    #[must_use]
1381    #[inline]
1382    pub const fn total_cmp(&self, other: &Self) -> crate::cmp::Ordering {
1383        let mut left = self.to_bits() as i32;
1384        let mut right = other.to_bits() as i32;
1385
1386        // In case of negatives, flip all the bits except the sign
1387        // to achieve a similar layout as two's complement integers
1388        //
1389        // Why does this work? IEEE 754 floats consist of three fields:
1390        // Sign bit, exponent and mantissa. The set of exponent and mantissa
1391        // fields as a whole have the property that their bitwise order is
1392        // equal to the numeric magnitude where the magnitude is defined.
1393        // The magnitude is not normally defined on NaN values, but
1394        // IEEE 754 totalOrder defines the NaN values also to follow the
1395        // bitwise order. This leads to order explained in the doc comment.
1396        // However, the representation of magnitude is the same for negative
1397        // and positive numbers – only the sign bit is different.
1398        // To easily compare the floats as signed integers, we need to
1399        // flip the exponent and mantissa bits in case of negative numbers.
1400        // We effectively convert the numbers to "two's complement" form.
1401        //
1402        // To do the flipping, we construct a mask and XOR against it.
1403        // We branchlessly calculate an "all-ones except for the sign bit"
1404        // mask from negative-signed values: right shifting sign-extends
1405        // the integer, so we "fill" the mask with sign bits, and then
1406        // convert to unsigned to push one more zero bit.
1407        // On positive values, the mask is all zeros, so it's a no-op.
1408        left ^= (((left >> 31) as u32) >> 1) as i32;
1409        right ^= (((right >> 31) as u32) >> 1) as i32;
1410
1411        left.cmp(&right)
1412    }
1413
1414    /// Restrict a value to a certain interval unless it is NaN.
1415    ///
1416    /// Returns `max` if `self` is greater than `max`, and `min` if `self` is
1417    /// less than `min`. Otherwise this returns `self`.
1418    ///
1419    /// Note that this function returns NaN if the initial value was NaN as
1420    /// well. If the result is zero and among the three inputs `self`, `min`, and `max` there are
1421    /// zeros with different sign, either `0.0` or `-0.0` is returned non-deterministically.
1422    ///
1423    /// # Panics
1424    ///
1425    /// Panics if `min > max`, `min` is NaN, or `max` is NaN.
1426    ///
1427    /// # Examples
1428    ///
1429    /// ```
1430    /// assert!((-3.0f32).clamp(-2.0, 1.0) == -2.0);
1431    /// assert!((0.0f32).clamp(-2.0, 1.0) == 0.0);
1432    /// assert!((2.0f32).clamp(-2.0, 1.0) == 1.0);
1433    /// assert!((f32::NAN).clamp(-2.0, 1.0).is_nan());
1434    ///
1435    /// // These always returns zero, but the sign (which is ignored by `==`) is non-deterministic.
1436    /// assert!((0.0f32).clamp(-0.0, -0.0) == 0.0);
1437    /// assert!((1.0f32).clamp(-0.0, 0.0) == 0.0);
1438    /// // This is definitely a negative zero.
1439    /// assert!((-1.0f32).clamp(-0.0, 1.0).is_sign_negative());
1440    /// ```
1441    #[must_use = "method returns a new number and does not mutate the original value"]
1442    #[stable(feature = "clamp", since = "1.50.0")]
1443    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1444    #[inline]
1445    pub const fn clamp(mut self, min: f32, max: f32) -> f32 {
1446        const_assert!(
1447            min <= max,
1448            "min > max, or either was NaN",
1449            "min > max, or either was NaN. min = {min:?}, max = {max:?}",
1450            min: f32,
1451            max: f32,
1452        );
1453
1454        if self < min {
1455            self = min;
1456        }
1457        if self > max {
1458            self = max;
1459        }
1460        self
1461    }
1462
1463    /// Clamps this number to a symmetric range centered around zero.
1464    ///
1465    /// The method clamps the number's magnitude (absolute value) to be at most `limit`.
1466    ///
1467    /// This is functionally equivalent to `self.clamp(-limit, limit)`, but is more
1468    /// explicit about the intent.
1469    ///
1470    /// # Panics
1471    ///
1472    /// Panics if `limit` is negative or NaN, as this indicates a logic error.
1473    ///
1474    /// # Examples
1475    ///
1476    /// ```
1477    /// #![feature(clamp_magnitude)]
1478    /// assert_eq!(5.0f32.clamp_magnitude(3.0), 3.0);
1479    /// assert_eq!((-5.0f32).clamp_magnitude(3.0), -3.0);
1480    /// assert_eq!(2.0f32.clamp_magnitude(3.0), 2.0);
1481    /// assert_eq!((-2.0f32).clamp_magnitude(3.0), -2.0);
1482    /// ```
1483    #[must_use = "this returns the clamped value and does not modify the original"]
1484    #[unstable(feature = "clamp_magnitude", issue = "148519")]
1485    #[inline]
1486    pub fn clamp_magnitude(self, limit: f32) -> f32 {
1487        assert!(limit >= 0.0, "limit must be non-negative");
1488        let limit = limit.abs(); // Canonicalises -0.0 to 0.0
1489        self.clamp(-limit, limit)
1490    }
1491
1492    /// Computes the absolute value of `self`.
1493    ///
1494    /// This function always returns the precise result.
1495    ///
1496    /// # Examples
1497    ///
1498    /// ```
1499    /// let x = 3.5_f32;
1500    /// let y = -3.5_f32;
1501    ///
1502    /// assert_eq!(x.abs(), x);
1503    /// assert_eq!(y.abs(), -y);
1504    ///
1505    /// assert!(f32::NAN.abs().is_nan());
1506    /// ```
1507    #[must_use = "method returns a new number and does not mutate the original value"]
1508    #[stable(feature = "rust1", since = "1.0.0")]
1509    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1510    #[inline]
1511    pub const fn abs(self) -> f32 {
1512        intrinsics::fabsf32(self)
1513    }
1514
1515    /// Returns a number that represents the sign of `self`.
1516    ///
1517    /// - `1.0` if the number is positive, `+0.0` or `INFINITY`
1518    /// - `-1.0` if the number is negative, `-0.0` or `NEG_INFINITY`
1519    /// - NaN if the number is NaN
1520    ///
1521    /// # Examples
1522    ///
1523    /// ```
1524    /// let f = 3.5_f32;
1525    ///
1526    /// assert_eq!(f.signum(), 1.0);
1527    /// assert_eq!(f32::NEG_INFINITY.signum(), -1.0);
1528    ///
1529    /// assert!(f32::NAN.signum().is_nan());
1530    /// ```
1531    #[must_use = "method returns a new number and does not mutate the original value"]
1532    #[stable(feature = "rust1", since = "1.0.0")]
1533    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1534    #[inline]
1535    pub const fn signum(self) -> f32 {
1536        if self.is_nan() { Self::NAN } else { 1.0_f32.copysign(self) }
1537    }
1538
1539    /// Returns a number composed of the magnitude of `self` and the sign of
1540    /// `sign`.
1541    ///
1542    /// Equal to `self` if the sign of `self` and `sign` are the same, otherwise equal to `-self`.
1543    /// If `self` is a NaN, then a NaN with the same payload as `self` and the sign bit of `sign` is
1544    /// returned.
1545    ///
1546    /// If `sign` is a NaN, then this operation will still carry over its sign into the result. Note
1547    /// that IEEE 754 doesn't assign any meaning to the sign bit in case of a NaN, and as Rust
1548    /// doesn't guarantee that the bit pattern of NaNs are conserved over arithmetic operations, the
1549    /// result of `copysign` with `sign` being a NaN might produce an unexpected or non-portable
1550    /// result. See the [specification of NaN bit patterns](primitive@f32#nan-bit-patterns) for more
1551    /// info.
1552    ///
1553    /// # Examples
1554    ///
1555    /// ```
1556    /// let f = 3.5_f32;
1557    ///
1558    /// assert_eq!(f.copysign(0.42), 3.5_f32);
1559    /// assert_eq!(f.copysign(-0.42), -3.5_f32);
1560    /// assert_eq!((-f).copysign(0.42), 3.5_f32);
1561    /// assert_eq!((-f).copysign(-0.42), -3.5_f32);
1562    ///
1563    /// assert!(f32::NAN.copysign(1.0).is_nan());
1564    /// ```
1565    #[must_use = "method returns a new number and does not mutate the original value"]
1566    #[inline]
1567    #[stable(feature = "copysign", since = "1.35.0")]
1568    #[rustc_const_stable(feature = "const_float_methods", since = "1.85.0")]
1569    pub const fn copysign(self, sign: f32) -> f32 {
1570        intrinsics::copysignf32(self, sign)
1571    }
1572
1573    /// Float addition that allows optimizations based on algebraic rules.
1574    ///
1575    /// See [algebraic operators](primitive@f32#algebraic-operators) for more info.
1576    #[must_use = "method returns a new number and does not mutate the original value"]
1577    #[unstable(feature = "float_algebraic", issue = "136469")]
1578    #[rustc_const_unstable(feature = "float_algebraic", issue = "136469")]
1579    #[inline]
1580    pub const fn algebraic_add(self, rhs: f32) -> f32 {
1581        intrinsics::fadd_algebraic(self, rhs)
1582    }
1583
1584    /// Float subtraction that allows optimizations based on algebraic rules.
1585    ///
1586    /// See [algebraic operators](primitive@f32#algebraic-operators) for more info.
1587    #[must_use = "method returns a new number and does not mutate the original value"]
1588    #[unstable(feature = "float_algebraic", issue = "136469")]
1589    #[rustc_const_unstable(feature = "float_algebraic", issue = "136469")]
1590    #[inline]
1591    pub const fn algebraic_sub(self, rhs: f32) -> f32 {
1592        intrinsics::fsub_algebraic(self, rhs)
1593    }
1594
1595    /// Float multiplication that allows optimizations based on algebraic rules.
1596    ///
1597    /// See [algebraic operators](primitive@f32#algebraic-operators) for more info.
1598    #[must_use = "method returns a new number and does not mutate the original value"]
1599    #[unstable(feature = "float_algebraic", issue = "136469")]
1600    #[rustc_const_unstable(feature = "float_algebraic", issue = "136469")]
1601    #[inline]
1602    pub const fn algebraic_mul(self, rhs: f32) -> f32 {
1603        intrinsics::fmul_algebraic(self, rhs)
1604    }
1605
1606    /// Float division that allows optimizations based on algebraic rules.
1607    ///
1608    /// See [algebraic operators](primitive@f32#algebraic-operators) for more info.
1609    #[must_use = "method returns a new number and does not mutate the original value"]
1610    #[unstable(feature = "float_algebraic", issue = "136469")]
1611    #[rustc_const_unstable(feature = "float_algebraic", issue = "136469")]
1612    #[inline]
1613    pub const fn algebraic_div(self, rhs: f32) -> f32 {
1614        intrinsics::fdiv_algebraic(self, rhs)
1615    }
1616
1617    /// Float remainder that allows optimizations based on algebraic rules.
1618    ///
1619    /// See [algebraic operators](primitive@f32#algebraic-operators) for more info.
1620    #[must_use = "method returns a new number and does not mutate the original value"]
1621    #[unstable(feature = "float_algebraic", issue = "136469")]
1622    #[rustc_const_unstable(feature = "float_algebraic", issue = "136469")]
1623    #[inline]
1624    pub const fn algebraic_rem(self, rhs: f32) -> f32 {
1625        intrinsics::frem_algebraic(self, rhs)
1626    }
1627}
1628
1629/// Experimental implementations of floating point functions in `core`.
1630///
1631/// _The standalone functions in this module are for testing only.
1632/// They will be stabilized as inherent methods._
1633#[unstable(feature = "core_float_math", issue = "137578")]
1634pub mod math {
1635    use crate::intrinsics;
1636    use crate::num::libm;
1637
1638    /// Experimental version of `floor` in `core`. See [`f32::floor`] for details.
1639    ///
1640    /// # Examples
1641    ///
1642    /// ```
1643    /// #![feature(core_float_math)]
1644    ///
1645    /// use core::f32;
1646    ///
1647    /// let f = 3.7_f32;
1648    /// let g = 3.0_f32;
1649    /// let h = -3.7_f32;
1650    ///
1651    /// assert_eq!(f32::math::floor(f), 3.0);
1652    /// assert_eq!(f32::math::floor(g), 3.0);
1653    /// assert_eq!(f32::math::floor(h), -4.0);
1654    /// ```
1655    ///
1656    /// _This standalone function is for testing only.
1657    /// It will be stabilized as an inherent method._
1658    ///
1659    /// [`f32::floor`]: ../../../std/primitive.f32.html#method.floor
1660    #[inline]
1661    #[unstable(feature = "core_float_math", issue = "137578")]
1662    #[must_use = "method returns a new number and does not mutate the original value"]
1663    pub const fn floor(x: f32) -> f32 {
1664        intrinsics::floorf32(x)
1665    }
1666
1667    /// Experimental version of `ceil` in `core`. See [`f32::ceil`] for details.
1668    ///
1669    /// # Examples
1670    ///
1671    /// ```
1672    /// #![feature(core_float_math)]
1673    ///
1674    /// use core::f32;
1675    ///
1676    /// let f = 3.01_f32;
1677    /// let g = 4.0_f32;
1678    ///
1679    /// assert_eq!(f32::math::ceil(f), 4.0);
1680    /// assert_eq!(f32::math::ceil(g), 4.0);
1681    /// ```
1682    ///
1683    /// _This standalone function is for testing only.
1684    /// It will be stabilized as an inherent method._
1685    ///
1686    /// [`f32::ceil`]: ../../../std/primitive.f32.html#method.ceil
1687    #[inline]
1688    #[doc(alias = "ceiling")]
1689    #[must_use = "method returns a new number and does not mutate the original value"]
1690    #[unstable(feature = "core_float_math", issue = "137578")]
1691    pub const fn ceil(x: f32) -> f32 {
1692        intrinsics::ceilf32(x)
1693    }
1694
1695    /// Experimental version of `round` in `core`. See [`f32::round`] for details.
1696    ///
1697    /// # Examples
1698    ///
1699    /// ```
1700    /// #![feature(core_float_math)]
1701    ///
1702    /// use core::f32;
1703    ///
1704    /// let f = 3.3_f32;
1705    /// let g = -3.3_f32;
1706    /// let h = -3.7_f32;
1707    /// let i = 3.5_f32;
1708    /// let j = 4.5_f32;
1709    ///
1710    /// assert_eq!(f32::math::round(f), 3.0);
1711    /// assert_eq!(f32::math::round(g), -3.0);
1712    /// assert_eq!(f32::math::round(h), -4.0);
1713    /// assert_eq!(f32::math::round(i), 4.0);
1714    /// assert_eq!(f32::math::round(j), 5.0);
1715    /// ```
1716    ///
1717    /// _This standalone function is for testing only.
1718    /// It will be stabilized as an inherent method._
1719    ///
1720    /// [`f32::round`]: ../../../std/primitive.f32.html#method.round
1721    #[inline]
1722    #[unstable(feature = "core_float_math", issue = "137578")]
1723    #[must_use = "method returns a new number and does not mutate the original value"]
1724    pub const fn round(x: f32) -> f32 {
1725        intrinsics::roundf32(x)
1726    }
1727
1728    /// Experimental version of `round_ties_even` in `core`. See [`f32::round_ties_even`] for
1729    /// details.
1730    ///
1731    /// # Examples
1732    ///
1733    /// ```
1734    /// #![feature(core_float_math)]
1735    ///
1736    /// use core::f32;
1737    ///
1738    /// let f = 3.3_f32;
1739    /// let g = -3.3_f32;
1740    /// let h = 3.5_f32;
1741    /// let i = 4.5_f32;
1742    ///
1743    /// assert_eq!(f32::math::round_ties_even(f), 3.0);
1744    /// assert_eq!(f32::math::round_ties_even(g), -3.0);
1745    /// assert_eq!(f32::math::round_ties_even(h), 4.0);
1746    /// assert_eq!(f32::math::round_ties_even(i), 4.0);
1747    /// ```
1748    ///
1749    /// _This standalone function is for testing only.
1750    /// It will be stabilized as an inherent method._
1751    ///
1752    /// [`f32::round_ties_even`]: ../../../std/primitive.f32.html#method.round_ties_even
1753    #[inline]
1754    #[unstable(feature = "core_float_math", issue = "137578")]
1755    #[must_use = "method returns a new number and does not mutate the original value"]
1756    pub const fn round_ties_even(x: f32) -> f32 {
1757        intrinsics::round_ties_even_f32(x)
1758    }
1759
1760    /// Experimental version of `trunc` in `core`. See [`f32::trunc`] for details.
1761    ///
1762    /// # Examples
1763    ///
1764    /// ```
1765    /// #![feature(core_float_math)]
1766    ///
1767    /// use core::f32;
1768    ///
1769    /// let f = 3.7_f32;
1770    /// let g = 3.0_f32;
1771    /// let h = -3.7_f32;
1772    ///
1773    /// assert_eq!(f32::math::trunc(f), 3.0);
1774    /// assert_eq!(f32::math::trunc(g), 3.0);
1775    /// assert_eq!(f32::math::trunc(h), -3.0);
1776    /// ```
1777    ///
1778    /// _This standalone function is for testing only.
1779    /// It will be stabilized as an inherent method._
1780    ///
1781    /// [`f32::trunc`]: ../../../std/primitive.f32.html#method.trunc
1782    #[inline]
1783    #[doc(alias = "truncate")]
1784    #[must_use = "method returns a new number and does not mutate the original value"]
1785    #[unstable(feature = "core_float_math", issue = "137578")]
1786    pub const fn trunc(x: f32) -> f32 {
1787        intrinsics::truncf32(x)
1788    }
1789
1790    /// Experimental version of `fract` in `core`. See [`f32::fract`] for details.
1791    ///
1792    /// # Examples
1793    ///
1794    /// ```
1795    /// #![feature(core_float_math)]
1796    ///
1797    /// use core::f32;
1798    ///
1799    /// let x = 3.6_f32;
1800    /// let y = -3.6_f32;
1801    /// let abs_difference_x = (f32::math::fract(x) - 0.6).abs();
1802    /// let abs_difference_y = (f32::math::fract(y) - (-0.6)).abs();
1803    ///
1804    /// assert!(abs_difference_x <= f32::EPSILON);
1805    /// assert!(abs_difference_y <= f32::EPSILON);
1806    /// ```
1807    ///
1808    /// _This standalone function is for testing only.
1809    /// It will be stabilized as an inherent method._
1810    ///
1811    /// [`f32::fract`]: ../../../std/primitive.f32.html#method.fract
1812    #[inline]
1813    #[unstable(feature = "core_float_math", issue = "137578")]
1814    #[must_use = "method returns a new number and does not mutate the original value"]
1815    pub const fn fract(x: f32) -> f32 {
1816        x - trunc(x)
1817    }
1818
1819    /// Experimental version of `mul_add` in `core`. See [`f32::mul_add`] for details.
1820    ///
1821    /// # Examples
1822    ///
1823    /// ```
1824    /// #![feature(core_float_math)]
1825    ///
1826    /// # // FIXME(#140515): mingw has an incorrect fma
1827    /// # // https://sourceforge.net/p/mingw-w64/bugs/848/
1828    /// # #[cfg(all(target_os = "windows", target_env = "gnu", not(target_abi = "llvm")))] {
1829    /// use core::f32;
1830    ///
1831    /// let m = 10.0_f32;
1832    /// let x = 4.0_f32;
1833    /// let b = 60.0_f32;
1834    ///
1835    /// assert_eq!(f32::math::mul_add(m, x, b), 100.0);
1836    /// assert_eq!(m * x + b, 100.0);
1837    ///
1838    /// let one_plus_eps = 1.0_f32 + f32::EPSILON;
1839    /// let one_minus_eps = 1.0_f32 - f32::EPSILON;
1840    /// let minus_one = -1.0_f32;
1841    ///
1842    /// // The exact result (1 + eps) * (1 - eps) = 1 - eps * eps.
1843    /// assert_eq!(
1844    ///     f32::math::mul_add(one_plus_eps, one_minus_eps, minus_one),
1845    ///     -f32::EPSILON * f32::EPSILON
1846    /// );
1847    /// // Different rounding with the non-fused multiply and add.
1848    /// assert_eq!(one_plus_eps * one_minus_eps + minus_one, 0.0);
1849    /// # }
1850    /// ```
1851    ///
1852    /// _This standalone function is for testing only.
1853    /// It will be stabilized as an inherent method._
1854    ///
1855    /// [`f32::mul_add`]: ../../../std/primitive.f32.html#method.mul_add
1856    #[inline]
1857    #[doc(alias = "fmaf", alias = "fusedMultiplyAdd")]
1858    #[must_use = "method returns a new number and does not mutate the original value"]
1859    #[unstable(feature = "core_float_math", issue = "137578")]
1860    pub const fn mul_add(x: f32, y: f32, z: f32) -> f32 {
1861        intrinsics::fmaf32(x, y, z)
1862    }
1863
1864    /// Experimental version of `div_euclid` in `core`. See [`f32::div_euclid`] for details.
1865    ///
1866    /// # Examples
1867    ///
1868    /// ```
1869    /// #![feature(core_float_math)]
1870    ///
1871    /// use core::f32;
1872    ///
1873    /// let a: f32 = 7.0;
1874    /// let b = 4.0;
1875    /// assert_eq!(f32::math::div_euclid(a, b), 1.0); // 7.0 > 4.0 * 1.0
1876    /// assert_eq!(f32::math::div_euclid(-a, b), -2.0); // -7.0 >= 4.0 * -2.0
1877    /// assert_eq!(f32::math::div_euclid(a, -b), -1.0); // 7.0 >= -4.0 * -1.0
1878    /// assert_eq!(f32::math::div_euclid(-a, -b), 2.0); // -7.0 >= -4.0 * 2.0
1879    /// ```
1880    ///
1881    /// _This standalone function is for testing only.
1882    /// It will be stabilized as an inherent method._
1883    ///
1884    /// [`f32::div_euclid`]: ../../../std/primitive.f32.html#method.div_euclid
1885    #[inline]
1886    #[unstable(feature = "core_float_math", issue = "137578")]
1887    #[must_use = "method returns a new number and does not mutate the original value"]
1888    pub fn div_euclid(x: f32, rhs: f32) -> f32 {
1889        let q = trunc(x / rhs);
1890        if x % rhs < 0.0 {
1891            return if rhs > 0.0 { q - 1.0 } else { q + 1.0 };
1892        }
1893        q
1894    }
1895
1896    /// Experimental version of `rem_euclid` in `core`. See [`f32::rem_euclid`] for details.
1897    ///
1898    /// # Examples
1899    ///
1900    /// ```
1901    /// #![feature(core_float_math)]
1902    ///
1903    /// use core::f32;
1904    ///
1905    /// let a: f32 = 7.0;
1906    /// let b = 4.0;
1907    /// assert_eq!(f32::math::rem_euclid(a, b), 3.0);
1908    /// assert_eq!(f32::math::rem_euclid(-a, b), 1.0);
1909    /// assert_eq!(f32::math::rem_euclid(a, -b), 3.0);
1910    /// assert_eq!(f32::math::rem_euclid(-a, -b), 1.0);
1911    /// // limitation due to round-off error
1912    /// assert!(f32::math::rem_euclid(-f32::EPSILON, 3.0) != 0.0);
1913    /// ```
1914    ///
1915    /// _This standalone function is for testing only.
1916    /// It will be stabilized as an inherent method._
1917    ///
1918    /// [`f32::rem_euclid`]: ../../../std/primitive.f32.html#method.rem_euclid
1919    #[inline]
1920    #[doc(alias = "modulo", alias = "mod")]
1921    #[unstable(feature = "core_float_math", issue = "137578")]
1922    #[must_use = "method returns a new number and does not mutate the original value"]
1923    pub fn rem_euclid(x: f32, rhs: f32) -> f32 {
1924        let r = x % rhs;
1925        if r < 0.0 { r + rhs.abs() } else { r }
1926    }
1927
1928    /// Experimental version of `powi` in `core`. See [`f32::powi`] for details.
1929    ///
1930    /// # Examples
1931    ///
1932    /// ```
1933    /// #![feature(core_float_math)]
1934    ///
1935    /// use core::f32;
1936    ///
1937    /// let x = 2.0_f32;
1938    /// let abs_difference = (f32::math::powi(x, 2) - (x * x)).abs();
1939    /// assert!(abs_difference <= 1e-5);
1940    ///
1941    /// assert_eq!(f32::math::powi(f32::NAN, 0), 1.0);
1942    /// ```
1943    ///
1944    /// _This standalone function is for testing only.
1945    /// It will be stabilized as an inherent method._
1946    ///
1947    /// [`f32::powi`]: ../../../std/primitive.f32.html#method.powi
1948    #[inline]
1949    #[must_use = "method returns a new number and does not mutate the original value"]
1950    #[unstable(feature = "core_float_math", issue = "137578")]
1951    pub fn powi(x: f32, n: i32) -> f32 {
1952        intrinsics::powif32(x, n)
1953    }
1954
1955    /// Experimental version of `sqrt` in `core`. See [`f32::sqrt`] for details.
1956    ///
1957    /// # Examples
1958    ///
1959    /// ```
1960    /// #![feature(core_float_math)]
1961    ///
1962    /// use core::f32;
1963    ///
1964    /// let positive = 4.0_f32;
1965    /// let negative = -4.0_f32;
1966    /// let negative_zero = -0.0_f32;
1967    ///
1968    /// assert_eq!(f32::math::sqrt(positive), 2.0);
1969    /// assert!(f32::math::sqrt(negative).is_nan());
1970    /// assert_eq!(f32::math::sqrt(negative_zero), negative_zero);
1971    /// ```
1972    ///
1973    /// _This standalone function is for testing only.
1974    /// It will be stabilized as an inherent method._
1975    ///
1976    /// [`f32::sqrt`]: ../../../std/primitive.f32.html#method.sqrt
1977    #[inline]
1978    #[doc(alias = "squareRoot")]
1979    #[unstable(feature = "core_float_math", issue = "137578")]
1980    #[must_use = "method returns a new number and does not mutate the original value"]
1981    pub fn sqrt(x: f32) -> f32 {
1982        intrinsics::sqrtf32(x)
1983    }
1984
1985    /// Experimental version of `abs_sub` in `core`. See [`f32::abs_sub`] for details.
1986    ///
1987    /// # Examples
1988    ///
1989    /// ```
1990    /// #![feature(core_float_math)]
1991    ///
1992    /// use core::f32;
1993    ///
1994    /// let x = 3.0f32;
1995    /// let y = -3.0f32;
1996    ///
1997    /// let abs_difference_x = (f32::math::abs_sub(x, 1.0) - 2.0).abs();
1998    /// let abs_difference_y = (f32::math::abs_sub(y, 1.0) - 0.0).abs();
1999    ///
2000    /// assert!(abs_difference_x <= 1e-6);
2001    /// assert!(abs_difference_y <= 1e-6);
2002    /// ```
2003    ///
2004    /// _This standalone function is for testing only.
2005    /// It will be stabilized as an inherent method._
2006    ///
2007    /// [`f32::abs_sub`]: ../../../std/primitive.f32.html#method.abs_sub
2008    #[inline]
2009    #[stable(feature = "rust1", since = "1.0.0")]
2010    #[deprecated(
2011        since = "1.10.0",
2012        note = "you probably meant `(self - other).abs()`: \
2013            this operation is `(self - other).max(0.0)` \
2014            except that `abs_sub` also propagates NaNs (also \
2015            known as `fdimf` in C). If you truly need the positive \
2016            difference, consider using that expression or the C function \
2017            `fdimf`, depending on how you wish to handle NaN (please consider \
2018            filing an issue describing your use-case too)."
2019    )]
2020    #[must_use = "method returns a new number and does not mutate the original value"]
2021    pub fn abs_sub(x: f32, other: f32) -> f32 {
2022        libm::fdimf(x, other)
2023    }
2024
2025    /// Experimental version of `cbrt` in `core`. See [`f32::cbrt`] for details.
2026    ///
2027    /// # Unspecified precision
2028    ///
2029    /// The precision of this function is non-deterministic. This means it varies by platform, Rust version, and
2030    /// can even differ within the same execution from one invocation to the next.
2031    /// This function currently corresponds to the `cbrtf` from libc on Unix
2032    /// and Windows. Note that this might change in the future.
2033    ///
2034    /// # Examples
2035    ///
2036    /// ```
2037    /// #![feature(core_float_math)]
2038    ///
2039    /// use core::f32;
2040    ///
2041    /// let x = 8.0f32;
2042    ///
2043    /// // x^(1/3) - 2 == 0
2044    /// let abs_difference = (f32::math::cbrt(x) - 2.0).abs();
2045    ///
2046    /// assert!(abs_difference <= 1e-6);
2047    /// ```
2048    ///
2049    /// _This standalone function is for testing only.
2050    /// It will be stabilized as an inherent method._
2051    ///
2052    /// [`f32::cbrt`]: ../../../std/primitive.f32.html#method.cbrt
2053    #[inline]
2054    #[must_use = "method returns a new number and does not mutate the original value"]
2055    #[unstable(feature = "core_float_math", issue = "137578")]
2056    pub fn cbrt(x: f32) -> f32 {
2057        libm::cbrtf(x)
2058    }
2059}