diff options
| -rw-r--r-- | library/std/src/f32.rs | 24 | ||||
| -rw-r--r-- | library/std/src/f64.rs | 24 |
2 files changed, 26 insertions, 22 deletions
diff --git a/library/std/src/f32.rs b/library/std/src/f32.rs index 6ec389400ae..de9bde51f2a 100644 --- a/library/std/src/f32.rs +++ b/library/std/src/f32.rs @@ -186,11 +186,8 @@ impl f32 { /// let x = 3.5_f32; /// let y = -3.5_f32; /// - /// let abs_difference_x = (x.abs() - x).abs(); - /// let abs_difference_y = (y.abs() - (-y)).abs(); - /// - /// assert!(abs_difference_x <= f32::EPSILON); - /// assert!(abs_difference_y <= f32::EPSILON); + /// assert_eq!(x.abs(), x); + /// assert_eq!(y.abs(), -y); /// /// assert!(f32::NAN.abs().is_nan()); /// ``` @@ -276,10 +273,17 @@ impl f32 { /// let x = 4.0_f32; /// let b = 60.0_f32; /// - /// // 100.0 - /// let abs_difference = (m.mul_add(x, b) - ((m * x) + b)).abs(); + /// assert_eq!(m.mul_add(x, b), 100.0); + /// assert_eq!(m * x + b, 100.0); /// - /// assert!(abs_difference <= f32::EPSILON); + /// let one_plus_eps = 1.0_f32 + f32::EPSILON; + /// let one_minus_eps = 1.0_f32 - f32::EPSILON; + /// let minus_one = -1.0_f32; + /// + /// // The exact result (1 + eps) * (1 - eps) = 1 - eps * eps. + /// assert_eq!(one_plus_eps.mul_add(one_minus_eps, minus_one), -f32::EPSILON * f32::EPSILON); + /// // Different rounding with the non-fused multiply and add. + /// assert_eq!(one_plus_eps * one_minus_eps + minus_one, 0.0); /// ``` #[rustc_allow_incoherent_impl] #[must_use = "method returns a new number and does not mutate the original value"] @@ -426,9 +430,7 @@ impl f32 { /// let negative = -4.0_f32; /// let negative_zero = -0.0_f32; /// - /// let abs_difference = (positive.sqrt() - 2.0).abs(); - /// - /// assert!(abs_difference <= f32::EPSILON); + /// assert_eq!(positive.sqrt(), 2.0); /// assert!(negative.sqrt().is_nan()); /// assert!(negative_zero.sqrt() == negative_zero); /// ``` diff --git a/library/std/src/f64.rs b/library/std/src/f64.rs index 7385576c337..944186d602c 100644 --- a/library/std/src/f64.rs +++ b/library/std/src/f64.rs @@ -186,11 +186,8 @@ impl f64 { /// let x = 3.5_f64; /// let y = -3.5_f64; /// - /// let abs_difference_x = (x.abs() - x).abs(); - /// let abs_difference_y = (y.abs() - (-y)).abs(); - /// - /// assert!(abs_difference_x < 1e-10); - /// assert!(abs_difference_y < 1e-10); + /// assert_eq!(x.abs(), x); + /// assert_eq!(y.abs(), -y); /// /// assert!(f64::NAN.abs().is_nan()); /// ``` @@ -276,10 +273,17 @@ impl f64 { /// let x = 4.0_f64; /// let b = 60.0_f64; /// - /// // 100.0 - /// let abs_difference = (m.mul_add(x, b) - ((m * x) + b)).abs(); + /// assert_eq!(m.mul_add(x, b), 100.0); + /// assert_eq!(m * x + b, 100.0); /// - /// assert!(abs_difference < 1e-10); + /// let one_plus_eps = 1.0_f64 + f64::EPSILON; + /// let one_minus_eps = 1.0_f64 - f64::EPSILON; + /// let minus_one = -1.0_f64; + /// + /// // The exact result (1 + eps) * (1 - eps) = 1 - eps * eps. + /// assert_eq!(one_plus_eps.mul_add(one_minus_eps, minus_one), -f64::EPSILON * f64::EPSILON); + /// // Different rounding with the non-fused multiply and add. + /// assert_eq!(one_plus_eps * one_minus_eps + minus_one, 0.0); /// ``` #[rustc_allow_incoherent_impl] #[must_use = "method returns a new number and does not mutate the original value"] @@ -426,9 +430,7 @@ impl f64 { /// let negative = -4.0_f64; /// let negative_zero = -0.0_f64; /// - /// let abs_difference = (positive.sqrt() - 2.0).abs(); - /// - /// assert!(abs_difference < 1e-10); + /// assert_eq!(positive.sqrt(), 2.0); /// assert!(negative.sqrt().is_nan()); /// assert!(negative_zero.sqrt() == negative_zero); /// ``` |