diff options
Diffstat (limited to 'library/std/src/f16.rs')
| -rw-r--r-- | library/std/src/f16.rs | 78 |
1 files changed, 76 insertions, 2 deletions
diff --git a/library/std/src/f16.rs b/library/std/src/f16.rs index cc523c93b4d..c3b51bf31de 100644 --- a/library/std/src/f16.rs +++ b/library/std/src/f16.rs @@ -1,4 +1,4 @@ -//! Constants for the `f16` double-precision floating point type. +//! Constants for the `f16` half-precision floating point type. //! //! *[See also the `f16` primitive type](primitive@f16).* //! @@ -126,7 +126,7 @@ impl f16 { #[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 { - unsafe { intrinsics::rintf16(self) } + intrinsics::round_ties_even_f16(self) } /// Returns the integer part of `self`. @@ -1224,6 +1224,7 @@ impl f16 { #[inline] #[rustc_allow_incoherent_impl] #[unstable(feature = "f16", issue = "116909")] + // #[unstable(feature = "float_gamma", issue = "99842")] #[must_use = "method returns a new number and does not mutate the original value"] pub fn gamma(self) -> f16 { (unsafe { cmath::tgammaf(self as f32) }) as f16 @@ -1258,10 +1259,83 @@ impl f16 { #[inline] #[rustc_allow_incoherent_impl] #[unstable(feature = "f16", issue = "116909")] + // #[unstable(feature = "float_gamma", issue = "99842")] #[must_use = "method returns a new number and does not mutate the original value"] pub fn ln_gamma(self) -> (f16, i32) { let mut signgamp: i32 = 0; let x = (unsafe { cmath::lgammaf_r(self as f32, &mut signgamp) }) as f16; (x, signgamp) } + + /// Error function. + /// + /// # 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 `erff` from libc on Unix + /// and Windows. Note that this might change in the future. + /// + /// # Examples + /// + /// ``` + /// #![feature(f16)] + /// #![feature(float_erf)] + /// # #[cfg(reliable_f16_math)] { + /// /// The error function relates what percent of a normal distribution lies + /// /// within `x` standard deviations (scaled by `1/sqrt(2)`). + /// fn within_standard_deviations(x: f16) -> f16 { + /// (x * std::f16::consts::FRAC_1_SQRT_2).erf() * 100.0 + /// } + /// + /// // 68% of a normal distribution is within one standard deviation + /// assert!((within_standard_deviations(1.0) - 68.269).abs() < 0.1); + /// // 95% of a normal distribution is within two standard deviations + /// assert!((within_standard_deviations(2.0) - 95.450).abs() < 0.1); + /// // 99.7% of a normal distribution is within three standard deviations + /// assert!((within_standard_deviations(3.0) - 99.730).abs() < 0.1); + /// # } + /// ``` + #[rustc_allow_incoherent_impl] + #[must_use = "method returns a new number and does not mutate the original value"] + #[unstable(feature = "f16", issue = "116909")] + // #[unstable(feature = "float_erf", issue = "136321")] + #[inline] + pub fn erf(self) -> f16 { + (unsafe { cmath::erff(self as f32) }) as f16 + } + + /// Complementary error function. + /// + /// # 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 `erfcf` from libc on Unix + /// and Windows. Note that this might change in the future. + /// + /// # Examples + /// + /// ``` + /// #![feature(f16)] + /// #![feature(float_erf)] + /// # #[cfg(reliable_f16_math)] { + /// let x: f16 = 0.123; + /// + /// let one = x.erf() + x.erfc(); + /// let abs_difference = (one - 1.0).abs(); + /// + /// assert!(abs_difference <= f16::EPSILON); + /// # } + /// ``` + #[rustc_allow_incoherent_impl] + #[must_use = "method returns a new number and does not mutate the original value"] + #[unstable(feature = "f16", issue = "116909")] + // #[unstable(feature = "float_erf", issue = "136321")] + #[inline] + pub fn erfc(self) -> f16 { + (unsafe { cmath::erfcf(self as f32) }) as f16 + } } |