return approximations for max float values in acosh and asinh

Author: malezjaa

library/coretests/tests/num/floats.rs

@@ -1699,6 +1699,8 @@ float_test! {
         assert!(nan.asinh().is_nan());
         assert!(flt(-0.0).asinh().is_sign_negative());
 
+        assert_ne!(Float::MAX.asinh(), inf);
+
         // issue 63271
         assert_approx_eq!(flt(2.0).asinh(), 1.443635475178810342493276740273105, Float::ASINH_APPROX);
         assert_approx_eq!(flt(-2.0).asinh(), -1.443635475178810342493276740273105, Float::ASINH_APPROX);
@@ -1732,6 +1734,7 @@ float_test! {
         assert!(nan.acosh().is_nan());
         assert_approx_eq!(flt(2.0).acosh(), 1.31695789692481670862504634730796844, Float::ACOSH_APPROX);
         assert_approx_eq!(flt(3.0).acosh(), 1.76274717403908605046521864995958461, Float::ACOSH_APPROX);
+        assert_ne!(Float::MAX.acosh(), inf);
 
         #[allow(overflowing_literals)]
         if Float::MAX > flt(66000.0) {

library/std/src/num/f128.rs

@@ -868,6 +868,10 @@ impl f128 {
     #[must_use = "method returns a new number and does not mutate the original value"]
     pub fn asinh(self) -> f128 {
         let ax = self.abs();
+        if ax >= (1u128 << f128::MANTISSA_DIGITS / 2) as f128 {
+            return (ax.ln() + consts::LN_2).copysign(self);
+        }
+
         let ix = 1.0 / ax;
         (ax + (ax / (Self::hypot(1.0, ix) + ix))).ln_1p().copysign(self)
     }
@@ -902,6 +906,8 @@ impl f128 {
     pub fn acosh(self) -> f128 {
         if self < 1.0 {
             Self::NAN
+        } else if self >= (1u128 << f128::MANTISSA_DIGITS / 2) as f128 {
+            self.ln() + consts::LN_2
         } else {
             (self + ((self - 1.0).sqrt() * (self + 1.0).sqrt())).ln()
         }

library/std/src/num/f16.rs

@@ -833,6 +833,10 @@ impl f16 {
     #[must_use = "method returns a new number and does not mutate the original value"]
     pub fn asinh(self) -> f16 {
         let ax = self.abs();
+        if ax >= (1u16 << f16::MANTISSA_DIGITS / 2) as f16 {
+            return (ax.ln() + consts::LN_2).copysign(self);
+        }
+
         let ix = 1.0 / ax;
         (ax + (ax / (Self::hypot(1.0, ix) + ix))).ln_1p().copysign(self)
     }
@@ -867,6 +871,8 @@ impl f16 {
     pub fn acosh(self) -> f16 {
         if self < 1.0 {
             Self::NAN
+        } else if self >= (1u16 << f16::MANTISSA_DIGITS / 2) as f16 {
+            self.ln() + consts::LN_2
         } else {
             (self + ((self - 1.0).sqrt() * (self + 1.0).sqrt())).ln()
         }

library/std/src/num/f32.rs

@@ -1092,6 +1092,10 @@ impl f32 {
     #[inline]
     pub fn asinh(self) -> f32 {
         let ax = self.abs();
+        if ax >= (1u32 << f32::MANTISSA_DIGITS / 2) as f32 {
+            return (ax.ln() + consts::LN_2).copysign(self);
+        }
+
         let ix = 1.0 / ax;
         (ax + (ax / (Self::hypot(1.0, ix) + ix))).ln_1p().copysign(self)
     }
@@ -1121,6 +1125,8 @@ impl f32 {
     pub fn acosh(self) -> f32 {
         if self < 1.0 {
             Self::NAN
+        } else if self >= (1u32 << f32::MANTISSA_DIGITS / 2) as f32 {
+            self.ln() + consts::LN_2
         } else {
             (self + ((self - 1.0).sqrt() * (self + 1.0).sqrt())).ln()
         }

library/std/src/num/f64.rs

@@ -1092,6 +1092,10 @@ impl f64 {
     #[inline]
     pub fn asinh(self) -> f64 {
         let ax = self.abs();
+        if ax >= (1u64 << f64::MANTISSA_DIGITS / 2) as f64 {
+            return (ax.ln() + consts::LN_2).copysign(self);
+        }
+
         let ix = 1.0 / ax;
         (ax + (ax / (Self::hypot(1.0, ix) + ix))).ln_1p().copysign(self)
     }
@@ -1121,6 +1125,8 @@ impl f64 {
     pub fn acosh(self) -> f64 {
         if self < 1.0 {
             Self::NAN
+        } else if self >= (1u64 << f64::MANTISSA_DIGITS / 2) as f64 {
+            self.ln() + consts::LN_2
         } else {
             (self + ((self - 1.0).sqrt() * (self + 1.0).sqrt())).ln()
         }