diff options
Diffstat (limited to 'library/core/src/num/f16.rs')
| -rw-r--r-- | library/core/src/num/f16.rs | 445 |
1 files changed, 445 insertions, 0 deletions
diff --git a/library/core/src/num/f16.rs b/library/core/src/num/f16.rs index e47900cba55..1a859f2277f 100644 --- a/library/core/src/num/f16.rs +++ b/library/core/src/num/f16.rs @@ -13,6 +13,8 @@ use crate::convert::FloatToInt; use crate::num::FpCategory; +#[cfg(not(test))] +use crate::num::libm; use crate::panic::const_assert; use crate::{intrinsics, mem}; @@ -1391,3 +1393,446 @@ impl f16 { intrinsics::frem_algebraic(self, rhs) } } + +// Functions in this module fall into `core_float_math` +// #[unstable(feature = "core_float_math", issue = "137578")] +#[cfg(not(test))] +impl f16 { + /// Returns the largest integer less than or equal to `self`. + /// + /// This function always returns the precise result. + /// + /// # Examples + /// + /// ``` + /// #![feature(f16)] + /// # #![feature(cfg_target_has_reliable_f16_f128)] + /// # #![expect(internal_features)] + /// # #[cfg(not(miri))] + /// # #[cfg(target_has_reliable_f16_math)] { + /// + /// let f = 3.7_f16; + /// let g = 3.0_f16; + /// let h = -3.7_f16; + /// + /// assert_eq!(f.floor(), 3.0); + /// assert_eq!(g.floor(), 3.0); + /// assert_eq!(h.floor(), -4.0); + /// # } + /// ``` + #[inline] + #[rustc_allow_incoherent_impl] + #[unstable(feature = "f16", issue = "116909")] + #[must_use = "method returns a new number and does not mutate the original value"] + pub fn floor(self) -> f16 { + // SAFETY: intrinsic with no preconditions + unsafe { intrinsics::floorf16(self) } + } + + /// Returns the smallest integer greater than or equal to `self`. + /// + /// This function always returns the precise result. + /// + /// # Examples + /// + /// ``` + /// #![feature(f16)] + /// # #![feature(cfg_target_has_reliable_f16_f128)] + /// # #![expect(internal_features)] + /// # #[cfg(not(miri))] + /// # #[cfg(target_has_reliable_f16_math)] { + /// + /// let f = 3.01_f16; + /// let g = 4.0_f16; + /// + /// assert_eq!(f.ceil(), 4.0); + /// assert_eq!(g.ceil(), 4.0); + /// # } + /// ``` + #[inline] + #[doc(alias = "ceiling")] + #[rustc_allow_incoherent_impl] + #[unstable(feature = "f16", issue = "116909")] + #[must_use = "method returns a new number and does not mutate the original value"] + pub fn ceil(self) -> f16 { + // SAFETY: intrinsic with no preconditions + unsafe { intrinsics::ceilf16(self) } + } + + /// Returns the nearest integer to `self`. If a value is half-way between two + /// integers, round away from `0.0`. + /// + /// This function always returns the precise result. + /// + /// # Examples + /// + /// ``` + /// #![feature(f16)] + /// # #![feature(cfg_target_has_reliable_f16_f128)] + /// # #![expect(internal_features)] + /// # #[cfg(not(miri))] + /// # #[cfg(target_has_reliable_f16_math)] { + /// + /// let f = 3.3_f16; + /// let g = -3.3_f16; + /// let h = -3.7_f16; + /// let i = 3.5_f16; + /// let j = 4.5_f16; + /// + /// assert_eq!(f.round(), 3.0); + /// assert_eq!(g.round(), -3.0); + /// assert_eq!(h.round(), -4.0); + /// assert_eq!(i.round(), 4.0); + /// assert_eq!(j.round(), 5.0); + /// # } + /// ``` + #[inline] + #[rustc_allow_incoherent_impl] + #[unstable(feature = "f16", issue = "116909")] + #[must_use = "method returns a new number and does not mutate the original value"] + pub fn round(self) -> f16 { + // SAFETY: intrinsic with no preconditions + unsafe { intrinsics::roundf16(self) } + } + + /// Returns the nearest integer to a number. Rounds half-way cases to the number + /// with an even least significant digit. + /// + /// This function always returns the precise result. + /// + /// # Examples + /// + /// ``` + /// #![feature(f16)] + /// # #![feature(cfg_target_has_reliable_f16_f128)] + /// # #![expect(internal_features)] + /// # #[cfg(not(miri))] + /// # #[cfg(target_has_reliable_f16_math)] { + /// + /// let f = 3.3_f16; + /// let g = -3.3_f16; + /// let h = 3.5_f16; + /// let i = 4.5_f16; + /// + /// assert_eq!(f.round_ties_even(), 3.0); + /// assert_eq!(g.round_ties_even(), -3.0); + /// assert_eq!(h.round_ties_even(), 4.0); + /// assert_eq!(i.round_ties_even(), 4.0); + /// # } + /// ``` + #[inline] + #[rustc_allow_incoherent_impl] + #[unstable(feature = "f16", issue = "116909")] + #[must_use = "method returns a new number and does not mutate the original value"] + pub fn round_ties_even(self) -> f16 { + intrinsics::round_ties_even_f16(self) + } + + /// Returns the integer part of `self`. + /// This means that non-integer numbers are always truncated towards zero. + /// + /// This function always returns the precise result. + /// + /// # Examples + /// + /// ``` + /// #![feature(f16)] + /// # #![feature(cfg_target_has_reliable_f16_f128)] + /// # #![expect(internal_features)] + /// # #[cfg(not(miri))] + /// # #[cfg(target_has_reliable_f16_math)] { + /// + /// let f = 3.7_f16; + /// let g = 3.0_f16; + /// let h = -3.7_f16; + /// + /// assert_eq!(f.trunc(), 3.0); + /// assert_eq!(g.trunc(), 3.0); + /// assert_eq!(h.trunc(), -3.0); + /// # } + /// ``` + #[inline] + #[doc(alias = "truncate")] + #[rustc_allow_incoherent_impl] + #[unstable(feature = "f16", issue = "116909")] + #[must_use = "method returns a new number and does not mutate the original value"] + pub fn trunc(self) -> f16 { + // SAFETY: intrinsic with no preconditions + unsafe { intrinsics::truncf16(self) } + } + + /// Returns the fractional part of `self`. + /// + /// This function always returns the precise result. + /// + /// # Examples + /// + /// ``` + /// #![feature(f16)] + /// # #![feature(cfg_target_has_reliable_f16_f128)] + /// # #![expect(internal_features)] + /// # #[cfg(not(miri))] + /// # #[cfg(target_has_reliable_f16_math)] { + /// + /// let x = 3.6_f16; + /// let y = -3.6_f16; + /// let abs_difference_x = (x.fract() - 0.6).abs(); + /// let abs_difference_y = (y.fract() - (-0.6)).abs(); + /// + /// assert!(abs_difference_x <= f16::EPSILON); + /// assert!(abs_difference_y <= f16::EPSILON); + /// # } + /// ``` + #[inline] + #[rustc_allow_incoherent_impl] + #[unstable(feature = "f16", issue = "116909")] + #[must_use = "method returns a new number and does not mutate the original value"] + pub fn fract(self) -> f16 { + self - self.trunc() + } + + /// Fused multiply-add. Computes `(self * a) + b` with only one rounding + /// error, yielding a more accurate result than an unfused multiply-add. + /// + /// Using `mul_add` *may* be more performant than an unfused multiply-add if + /// the target architecture has a dedicated `fma` CPU instruction. However, + /// this is not always true, and will be heavily dependant on designing + /// algorithms with specific target hardware in mind. + /// + /// # Precision + /// + /// The result of this operation is guaranteed to be the rounded + /// infinite-precision result. It is specified by IEEE 754 as + /// `fusedMultiplyAdd` and guaranteed not to change. + /// + /// # Examples + /// + /// ``` + /// #![feature(f16)] + /// # #![feature(cfg_target_has_reliable_f16_f128)] + /// # #![expect(internal_features)] + /// # #[cfg(not(miri))] + /// # #[cfg(target_has_reliable_f16_math)] { + /// + /// let m = 10.0_f16; + /// let x = 4.0_f16; + /// let b = 60.0_f16; + /// + /// assert_eq!(m.mul_add(x, b), 100.0); + /// assert_eq!(m * x + b, 100.0); + /// + /// let one_plus_eps = 1.0_f16 + f16::EPSILON; + /// let one_minus_eps = 1.0_f16 - f16::EPSILON; + /// let minus_one = -1.0_f16; + /// + /// // The exact result (1 + eps) * (1 - eps) = 1 - eps * eps. + /// assert_eq!(one_plus_eps.mul_add(one_minus_eps, minus_one), -f16::EPSILON * f16::EPSILON); + /// // Different rounding with the non-fused multiply and add. + /// assert_eq!(one_plus_eps * one_minus_eps + minus_one, 0.0); + /// # } + /// ``` + #[inline] + #[rustc_allow_incoherent_impl] + #[unstable(feature = "f16", issue = "116909")] + #[doc(alias = "fmaf16", alias = "fusedMultiplyAdd")] + #[must_use = "method returns a new number and does not mutate the original value"] + pub fn mul_add(self, a: f16, b: f16) -> f16 { + // SAFETY: intrinsic with no preconditions + unsafe { intrinsics::fmaf16(self, a, b) } + } + + /// Calculates Euclidean division, the matching method for `rem_euclid`. + /// + /// This computes the integer `n` such that + /// `self = n * rhs + self.rem_euclid(rhs)`. + /// In other words, the result is `self / rhs` rounded to the integer `n` + /// such that `self >= n * rhs`. + /// + /// # Precision + /// + /// The result of this operation is guaranteed to be the rounded + /// infinite-precision result. + /// + /// # Examples + /// + /// ``` + /// #![feature(f16)] + /// # #![feature(cfg_target_has_reliable_f16_f128)] + /// # #![expect(internal_features)] + /// # #[cfg(not(miri))] + /// # #[cfg(target_has_reliable_f16_math)] { + /// + /// let a: f16 = 7.0; + /// let b = 4.0; + /// assert_eq!(a.div_euclid(b), 1.0); // 7.0 > 4.0 * 1.0 + /// assert_eq!((-a).div_euclid(b), -2.0); // -7.0 >= 4.0 * -2.0 + /// assert_eq!(a.div_euclid(-b), -1.0); // 7.0 >= -4.0 * -1.0 + /// assert_eq!((-a).div_euclid(-b), 2.0); // -7.0 >= -4.0 * 2.0 + /// # } + /// ``` + #[inline] + #[rustc_allow_incoherent_impl] + #[unstable(feature = "f16", issue = "116909")] + #[must_use = "method returns a new number and does not mutate the original value"] + pub fn div_euclid(self, rhs: f16) -> f16 { + let q = (self / rhs).trunc(); + if self % rhs < 0.0 { + return if rhs > 0.0 { q - 1.0 } else { q + 1.0 }; + } + q + } + + /// Calculates the least nonnegative remainder of `self (mod rhs)`. + /// + /// In particular, the return value `r` satisfies `0.0 <= r < rhs.abs()` in + /// most cases. However, due to a floating point round-off error it can + /// result in `r == rhs.abs()`, violating the mathematical definition, if + /// `self` is much smaller than `rhs.abs()` in magnitude and `self < 0.0`. + /// This result is not an element of the function's codomain, but it is the + /// closest floating point number in the real numbers and thus fulfills the + /// property `self == self.div_euclid(rhs) * rhs + self.rem_euclid(rhs)` + /// approximately. + /// + /// # Precision + /// + /// The result of this operation is guaranteed to be the rounded + /// infinite-precision result. + /// + /// # Examples + /// + /// ``` + /// #![feature(f16)] + /// # #![feature(cfg_target_has_reliable_f16_f128)] + /// # #![expect(internal_features)] + /// # #[cfg(not(miri))] + /// # #[cfg(target_has_reliable_f16_math)] { + /// + /// let a: f16 = 7.0; + /// let b = 4.0; + /// assert_eq!(a.rem_euclid(b), 3.0); + /// assert_eq!((-a).rem_euclid(b), 1.0); + /// assert_eq!(a.rem_euclid(-b), 3.0); + /// assert_eq!((-a).rem_euclid(-b), 1.0); + /// // limitation due to round-off error + /// assert!((-f16::EPSILON).rem_euclid(3.0) != 0.0); + /// # } + /// ``` + #[inline] + #[rustc_allow_incoherent_impl] + #[doc(alias = "modulo", alias = "mod")] + #[unstable(feature = "f16", issue = "116909")] + #[must_use = "method returns a new number and does not mutate the original value"] + pub fn rem_euclid(self, rhs: f16) -> f16 { + let r = self % rhs; + if r < 0.0 { r + rhs.abs() } else { r } + } + + /// Raises a number to an integer power. + /// + /// Using this function is generally faster than using `powf`. + /// It might have a different sequence of rounding operations than `powf`, + /// so the results are not guaranteed to agree. + /// + /// # Unspecified precision + /// + /// The precision of this function is non-deterministic. This means it varies by platform, + /// Rust version, and can even differ within the same execution from one invocation to the next. + /// + /// # Examples + /// + /// ``` + /// #![feature(f16)] + /// # #![feature(cfg_target_has_reliable_f16_f128)] + /// # #![expect(internal_features)] + /// # #[cfg(not(miri))] + /// # #[cfg(target_has_reliable_f16_math)] { + /// + /// let x = 2.0_f16; + /// let abs_difference = (x.powi(2) - (x * x)).abs(); + /// assert!(abs_difference <= f16::EPSILON); + /// + /// assert_eq!(f16::powi(f16::NAN, 0), 1.0); + /// # } + /// ``` + #[inline] + #[rustc_allow_incoherent_impl] + #[unstable(feature = "f16", issue = "116909")] + #[must_use = "method returns a new number and does not mutate the original value"] + pub fn powi(self, n: i32) -> f16 { + // SAFETY: intrinsic with no preconditions + unsafe { intrinsics::powif16(self, n) } + } + + /// Returns the square root of a number. + /// + /// Returns NaN if `self` is a negative number other than `-0.0`. + /// + /// # Precision + /// + /// The result of this operation is guaranteed to be the rounded + /// infinite-precision result. It is specified by IEEE 754 as `squareRoot` + /// and guaranteed not to change. + /// + /// # Examples + /// + /// ``` + /// #![feature(f16)] + /// # #![feature(cfg_target_has_reliable_f16_f128)] + /// # #![expect(internal_features)] + /// # #[cfg(not(miri))] + /// # #[cfg(target_has_reliable_f16_math)] { + /// + /// let positive = 4.0_f16; + /// let negative = -4.0_f16; + /// let negative_zero = -0.0_f16; + /// + /// assert_eq!(positive.sqrt(), 2.0); + /// assert!(negative.sqrt().is_nan()); + /// assert!(negative_zero.sqrt() == negative_zero); + /// # } + /// ``` + #[inline] + #[doc(alias = "squareRoot")] + #[rustc_allow_incoherent_impl] + #[unstable(feature = "f16", issue = "116909")] + #[must_use = "method returns a new number and does not mutate the original value"] + pub fn sqrt(self) -> f16 { + // SAFETY: intrinsic with no preconditions + unsafe { intrinsics::sqrtf16(self) } + } + + /// Returns the cube root of a number. + /// + /// # Unspecified precision + /// + /// The precision of this function is non-deterministic. This means it varies by platform, + /// Rust version, and can even differ within the same execution from one invocation to the next. + /// + /// This function currently corresponds to the `cbrtf` from libc on Unix + /// and Windows. Note that this might change in the future. + /// + /// # Examples + /// + /// ``` + /// #![feature(f16)] + /// # #![feature(cfg_target_has_reliable_f16_f128)] + /// # #![expect(internal_features)] + /// # #[cfg(not(miri))] + /// # #[cfg(target_has_reliable_f16_math)] { + /// + /// let x = 8.0f16; + /// + /// // x^(1/3) - 2 == 0 + /// let abs_difference = (x.cbrt() - 2.0).abs(); + /// + /// assert!(abs_difference <= f16::EPSILON); + /// # } + /// ``` + #[inline] + #[rustc_allow_incoherent_impl] + #[unstable(feature = "f16", issue = "116909")] + #[must_use = "method returns a new number and does not mutate the original value"] + pub fn cbrt(self) -> f16 { + libm::cbrtf(self as f32) as f16 + } +} |