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Fixed floating point issue with asinh function #63698

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merged 5 commits into from
Aug 27, 2019
Merged

Fixed floating point issue with asinh function #63698

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92f08b7
Merge pull request #1 from rust-lang/master
Phosphorus15 Aug 19, 2019
c456934
Added negative cases for `asinh` according to IEEE-754.
Phosphorus15 Aug 19, 2019
64e3a10
test cases for both `f32` and `f64` on asinh(-0.0)
Phosphorus15 Aug 19, 2019
535efa4
Used `copysign` to avoid unnecessary branches.
Phosphorus15 Aug 20, 2019
e33d870
Refined implementations of `asinh` and `acosh`
Phosphorus15 Aug 20, 2019
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10 changes: 6 additions & 4 deletions src/libstd/f32.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -911,7 +911,7 @@ impl f32 {
if self == NEG_INFINITY {
NEG_INFINITY
} else {
(self + ((self * self) + 1.0).sqrt()).ln()
(self + ((self * self) + 1.0).sqrt()).ln().copysign(self)
}
}

Expand All @@ -932,9 +932,10 @@ impl f32 {
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
pub fn acosh(self) -> f32 {
match self {
x if x < 1.0 => crate::f32::NAN,
x => (x + ((x * x) - 1.0).sqrt()).ln(),
if self < 1.0 {
crate::f32::NAN
} else {
(self + ((self * self) - 1.0).sqrt()).ln()
}
}

Expand Down Expand Up @@ -1488,6 +1489,7 @@ mod tests {
assert_eq!(inf.asinh(), inf);
assert_eq!(neg_inf.asinh(), neg_inf);
assert!(nan.asinh().is_nan());
assert!((-0.0f32).asinh().is_sign_negative()); // issue 63271
assert_approx_eq!(2.0f32.asinh(), 1.443635475178810342493276740273105f32);
assert_approx_eq!((-2.0f32).asinh(), -1.443635475178810342493276740273105f32);
}
Expand Down
33 changes: 18 additions & 15 deletions src/libstd/f64.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -244,7 +244,7 @@ impl f64 {
pub fn div_euclid(self, rhs: f64) -> f64 {
let q = (self / rhs).trunc();
if self % rhs < 0.0 {
return if rhs > 0.0 { q - 1.0 } else { q + 1.0 }
return if rhs > 0.0 { q - 1.0 } else { q + 1.0 };
}
q
}
Expand Down Expand Up @@ -437,9 +437,9 @@ impl f64 {
pub fn log2(self) -> f64 {
self.log_wrapper(|n| {
#[cfg(target_os = "android")]
return crate::sys::android::log2f64(n);
return crate::sys::android::log2f64(n);
#[cfg(not(target_os = "android"))]
return unsafe { intrinsics::log2f64(n) };
return unsafe { intrinsics::log2f64(n) };
})
}

Expand Down Expand Up @@ -481,16 +481,16 @@ impl f64 {
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
#[rustc_deprecated(since = "1.10.0",
reason = "you probably meant `(self - other).abs()`: \
reason = "you probably meant `(self - other).abs()`: \
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Why?

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Sorry for changing the identation 😢 , it might because of my IDE's formatter.

this operation is `(self - other).max(0.0)` \
except that `abs_sub` also propagates NaNs (also \
known as `fdim` in C). If you truly need the positive \
difference, consider using that expression or the C function \
`fdim`, depending on how you wish to handle NaN (please consider \
filing an issue describing your use-case too).")]
pub fn abs_sub(self, other: f64) -> f64 {
unsafe { cmath::fdim(self, other) }
}
pub fn abs_sub(self, other: f64) -> f64 {
unsafe { cmath::fdim(self, other) }
}

/// Takes the cubic root of a number.
///
Expand Down Expand Up @@ -834,7 +834,7 @@ impl f64 {
if self == NEG_INFINITY {
NEG_INFINITY
} else {
(self + ((self * self) + 1.0).sqrt()).ln()
(self + ((self * self) + 1.0).sqrt()).ln().copysign(self)
}
}

Expand All @@ -853,9 +853,10 @@ impl f64 {
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
pub fn acosh(self) -> f64 {
match self {
x if x < 1.0 => NAN,
x => (x + ((x * x) - 1.0).sqrt()).ln(),
if self < 1.0 {
NAN
} else {
(self + ((self * self) - 1.0).sqrt()).ln()
}
}

Expand Down Expand Up @@ -1188,7 +1189,7 @@ mod tests {
assert_eq!((-0f64).abs(), 0f64);
assert_eq!((-1f64).abs(), 1f64);
assert_eq!(NEG_INFINITY.abs(), INFINITY);
assert_eq!((1f64/NEG_INFINITY).abs(), 0f64);
assert_eq!((1f64 / NEG_INFINITY).abs(), 0f64);
assert!(NAN.abs().is_nan());
}

Expand All @@ -1200,7 +1201,7 @@ mod tests {
assert_eq!((-0f64).signum(), -1f64);
assert_eq!((-1f64).signum(), -1f64);
assert_eq!(NEG_INFINITY.signum(), -1f64);
assert_eq!((1f64/NEG_INFINITY).signum(), -1f64);
assert_eq!((1f64 / NEG_INFINITY).signum(), -1f64);
assert!(NAN.signum().is_nan());
}

Expand All @@ -1212,7 +1213,7 @@ mod tests {
assert!(!(-0f64).is_sign_positive());
assert!(!(-1f64).is_sign_positive());
assert!(!NEG_INFINITY.is_sign_positive());
assert!(!(1f64/NEG_INFINITY).is_sign_positive());
assert!(!(1f64 / NEG_INFINITY).is_sign_positive());
assert!(NAN.is_sign_positive());
assert!(!(-NAN).is_sign_positive());
}
Expand All @@ -1225,7 +1226,7 @@ mod tests {
assert!((-0f64).is_sign_negative());
assert!((-1f64).is_sign_negative());
assert!(NEG_INFINITY.is_sign_negative());
assert!((1f64/NEG_INFINITY).is_sign_negative());
assert!((1f64 / NEG_INFINITY).is_sign_negative());
assert!(!NAN.is_sign_negative());
assert!((-NAN).is_sign_negative());
}
Expand Down Expand Up @@ -1434,6 +1435,8 @@ mod tests {
assert_eq!(inf.asinh(), inf);
assert_eq!(neg_inf.asinh(), neg_inf);
assert!(nan.asinh().is_nan());
assert!((-0.0f64).asinh().is_sign_negative());
// issue 63271
assert_approx_eq!(2.0f64.asinh(), 1.443635475178810342493276740273105f64);
assert_approx_eq!((-2.0f64).asinh(), -1.443635475178810342493276740273105f64);
}
Expand Down