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Expand pow docs with special-case tests #148526

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34 changes: 33 additions & 1 deletion library/core/src/num/f128.rs
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Expand Up @@ -1769,7 +1769,39 @@ impl f128 {
/// let abs_difference = (x.powi(2) - (x * x)).abs();
/// assert!(abs_difference <= f128::EPSILON);
///
/// assert_eq!(f128::powi(f128::NAN, 0), 1.0);
/// // Special cases:
/// // pow(x, ±0) = 1 for any x
/// assert_eq!(f128::powi(3.0, 0), 1.0);
///
/// // pow(1, y) = 1 for any y
/// assert_eq!(f128::powi(1.0, 2), 1.0);
///
/// // pow(x, 1) = x for any x
/// assert_eq!(f128::powi(3.0, 1), 3.0);
///
/// // pow(NaN, y) = NaN
/// assert!(f128::powi(f128::NAN, 2).is_nan());
///
/// // pow(±0, y) = ±Inf for y an odd integer < 0
/// assert_eq!(f128::powi(0.0, -3), f128::INFINITY);
///
/// // pow(±0, y) = +Inf for finite y < 0 and not an odd integer
/// assert_eq!(f128::powi(0.0, -2), f128::INFINITY);
///
/// // pow(±0, y) = ±0 for y an odd integer > 0
/// assert_eq!(f128::powi(-0.0, 3), -0.0);
///
/// // pow(±0, y) = +0 for finite y > 0 and not an odd integer
/// assert_eq!(f128::powi(0.0, 2), 0.0);
///
/// // pow(+Inf, y) = +Inf for y > 0
/// assert_eq!(f128::powi(f128::INFINITY, 2), f128::INFINITY);
///
/// // pow(+Inf, y) = +0 for y < 0
/// assert_eq!(f128::powi(f128::INFINITY, -2), 0.0);
///
/// // pow(-Inf, y) = pow(-0, -y)
/// assert_eq!(f128::powi(f128::NEG_INFINITY, 2), f128::powi(-0.0, -2));
/// # }
/// ```
#[inline]
Expand Down
34 changes: 33 additions & 1 deletion library/core/src/num/f16.rs
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Expand Up @@ -1744,7 +1744,39 @@ impl f16 {
/// let abs_difference = (x.powi(2) - (x * x)).abs();
/// assert!(abs_difference <= f16::EPSILON);
///
/// assert_eq!(f16::powi(f16::NAN, 0), 1.0);
/// // Special cases:
/// // pow(x, ±0) = 1 for any x
/// assert_eq!(f16::powi(3.0, 0), 1.0);
///
/// // pow(1, y) = 1 for any y
/// assert_eq!(f16::powi(1.0, 2), 1.0);
///
/// // pow(x, 1) = x for any x
/// assert_eq!(f16::powi(3.0, 1), 3.0);
///
/// // pow(NaN, y) = NaN
/// assert!(f16::powi(f16::NAN, 2).is_nan());
///
/// // pow(±0, y) = ±Inf for y an odd integer < 0
/// assert_eq!(f16::powi(0.0, -3), f16::INFINITY);
///
/// // pow(±0, y) = +Inf for finite y < 0 and not an odd integer
/// assert_eq!(f16::powi(0.0, -2), f16::INFINITY);
///
/// // pow(±0, y) = ±0 for y an odd integer > 0
/// assert_eq!(f16::powi(-0.0, 3), -0.0);
///
/// // pow(±0, y) = +0 for finite y > 0 and not an odd integer
/// assert_eq!(f16::powi(0.0, 2), 0.0);
///
/// // pow(+Inf, y) = +Inf for y > 0
/// assert_eq!(f16::powi(f16::INFINITY, 2), f16::INFINITY);
///
/// // pow(+Inf, y) = +0 for y < 0
/// assert_eq!(f16::powi(f16::INFINITY, -2), 0.0);
///
/// // pow(-Inf, y) = pow(-0, -y)
/// assert_eq!(f16::powi(f16::NEG_INFINITY, 2), f16::powi(-0.0, -2));
/// # }
/// ```
#[inline]
Expand Down
78 changes: 78 additions & 0 deletions library/core/src/num/int_macros.rs
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Expand Up @@ -1715,6 +1715,19 @@ macro_rules! int_impl {
/// ```
#[doc = concat!("assert_eq!(8", stringify!($SelfT), ".checked_pow(2), Some(64));")]
#[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.checked_pow(2), None);")]
///
/// // Special cases:
/// // any `self` to the power of zero always returns 1.
#[doc = concat!("assert_eq!(3_", stringify!($SelfT), ".checked_pow(0), Some(1));")]
///
/// // 1 to the power of any `exp` always returns 1.
#[doc = concat!("assert_eq!(1_", stringify!($SelfT), ".checked_pow(2), Some(1));")]
///
/// // any `self` to the power of one always returns `self`.
#[doc = concat!("assert_eq!(3_", stringify!($SelfT), ".checked_pow(1), Some(3));")]
///
/// // 0 to the power of any `exp` always returns 0.
#[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".checked_pow(3), Some(0));")]
/// ```

#[stable(feature = "no_panic_pow", since = "1.34.0")]
Expand Down Expand Up @@ -1755,6 +1768,19 @@ macro_rules! int_impl {
///
/// ```
#[doc = concat!("assert_eq!(8", stringify!($SelfT), ".strict_pow(2), 64);")]
///
/// // Special cases:
/// // any `self` to the power of zero always returns 1.
#[doc = concat!("assert_eq!(3_", stringify!($SelfT), ".strict_pow(0), 1);")]
///
/// // 1 to the power of any `exp` always returns 1.
#[doc = concat!("assert_eq!(1_", stringify!($SelfT), ".strict_pow(2), 1);")]
///
/// // any `self` to the power of one always returns `self`.
#[doc = concat!("assert_eq!(3_", stringify!($SelfT), ".strict_pow(1), 3);")]
///
/// // 0 to the power of any `exp` always returns 0.
#[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".strict_pow(3), 0);")]
/// ```
///
/// The following panics because of overflow:
Expand Down Expand Up @@ -2029,6 +2055,19 @@ macro_rules! int_impl {
#[doc = concat!("assert_eq!((-4", stringify!($SelfT), ").saturating_pow(3), -64);")]
#[doc = concat!("assert_eq!(", stringify!($SelfT), "::MIN.saturating_pow(2), ", stringify!($SelfT), "::MAX);")]
#[doc = concat!("assert_eq!(", stringify!($SelfT), "::MIN.saturating_pow(3), ", stringify!($SelfT), "::MIN);")]
///
/// // Special cases:
/// // any `self` to the power of zero always returns 1.
#[doc = concat!("assert_eq!(3_", stringify!($SelfT), ".saturating_pow(0), 1);")]
///
/// // 1 to the power of any `exp` always returns 1.
#[doc = concat!("assert_eq!(1_", stringify!($SelfT), ".saturating_pow(2), 1);")]
///
/// // any `self` to the power of one always returns `self`.
#[doc = concat!("assert_eq!(3_", stringify!($SelfT), ".saturating_pow(1), 3);")]
///
/// // 0 to the power of any `exp` always returns 0.
#[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".saturating_pow(3), 0);")]
/// ```
#[stable(feature = "no_panic_pow", since = "1.34.0")]
#[rustc_const_stable(feature = "const_int_pow", since = "1.50.0")]
Expand Down Expand Up @@ -2371,6 +2410,19 @@ macro_rules! int_impl {
#[doc = concat!("assert_eq!(3", stringify!($SelfT), ".wrapping_pow(4), 81);")]
/// assert_eq!(3i8.wrapping_pow(5), -13);
/// assert_eq!(3i8.wrapping_pow(6), -39);
///
/// // Special cases:
/// // any `self` to the power of zero always returns 1.
#[doc = concat!("assert_eq!(3_", stringify!($SelfT), ".wrapping_pow(0), 1);")]
///
/// // 1 to the power of any `exp` always returns 1.
#[doc = concat!("assert_eq!(1_", stringify!($SelfT), ".wrapping_pow(2), 1);")]
///
/// // any `self` to the power of one always returns `self`.
#[doc = concat!("assert_eq!(3_", stringify!($SelfT), ".wrapping_pow(1), 3);")]
///
/// // 0 to the power of any `exp` always returns 0.
#[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".wrapping_pow(3), 0);")]
/// ```
#[stable(feature = "no_panic_pow", since = "1.34.0")]
#[rustc_const_stable(feature = "const_int_pow", since = "1.50.0")]
Expand Down Expand Up @@ -2962,6 +3014,19 @@ macro_rules! int_impl {
/// ```
#[doc = concat!("assert_eq!(3", stringify!($SelfT), ".overflowing_pow(4), (81, false));")]
/// assert_eq!(3i8.overflowing_pow(5), (-13, true));
///
/// // Special cases:
/// // any `self` to the power of zero always returns 1.
#[doc = concat!("assert_eq!(3_", stringify!($SelfT), ".overflowing_pow(0), (1, false));")]
///
/// // 1 to the power of any `exp` always returns 1.
#[doc = concat!("assert_eq!(1_", stringify!($SelfT), ".overflowing_pow(2), (1, false));")]
///
/// // any `self` to the power of one always returns `self`.
#[doc = concat!("assert_eq!(3_", stringify!($SelfT), ".overflowing_pow(1), (3, false));")]
///
/// // 0 to the power of any `exp` always returns 0.
#[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".overflowing_pow(3), (0, false));")]
/// ```
#[stable(feature = "no_panic_pow", since = "1.34.0")]
#[rustc_const_stable(feature = "const_int_pow", since = "1.50.0")]
Expand Down Expand Up @@ -3004,6 +3069,19 @@ macro_rules! int_impl {
#[doc = concat!("let x: ", stringify!($SelfT), " = 2; // or any other integer type")]
///
/// assert_eq!(x.pow(5), 32);
///
/// // Special cases:
/// // any `self` to the power of zero always returns 1.
#[doc = concat!("assert_eq!(3_", stringify!($SelfT), ".pow(0), 1);")]
///
/// // 1 to the power of any `exp` always returns 1.
#[doc = concat!("assert_eq!(1_", stringify!($SelfT), ".pow(2), 1);")]
///
/// // any `self` to the power of one always returns `self`.
#[doc = concat!("assert_eq!(3_", stringify!($SelfT), ".pow(1), 3);")]
///
/// // 0 to the power of any `exp` always returns 0.
#[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".pow(3), 0);")]
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_const_stable(feature = "const_int_pow", since = "1.50.0")]
Expand Down
78 changes: 78 additions & 0 deletions library/core/src/num/uint_macros.rs
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Expand Up @@ -2058,6 +2058,19 @@ macro_rules! uint_impl {
/// ```
#[doc = concat!("assert_eq!(2", stringify!($SelfT), ".checked_pow(5), Some(32));")]
#[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.checked_pow(2), None);")]
///
/// // Special cases:
/// // any `self` to the power of zero always returns 1.
#[doc = concat!("assert_eq!(3_", stringify!($SelfT), ".checked_pow(0), Some(1));")]
///
/// // 1 to the power of any `exp` always returns 1.
#[doc = concat!("assert_eq!(1_", stringify!($SelfT), ".checked_pow(2), Some(1));")]
///
/// // any `self` to the power of one always returns `self`.
#[doc = concat!("assert_eq!(3_", stringify!($SelfT), ".checked_pow(1), Some(3));")]
///
/// // 0 to the power of any `exp` always returns 0.
#[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".checked_pow(3), Some(0));")]
/// ```
#[stable(feature = "no_panic_pow", since = "1.34.0")]
#[rustc_const_stable(feature = "const_int_pow", since = "1.50.0")]
Expand Down Expand Up @@ -2097,6 +2110,19 @@ macro_rules! uint_impl {
///
/// ```
#[doc = concat!("assert_eq!(2", stringify!($SelfT), ".strict_pow(5), 32);")]
///
/// // Special cases:
/// // any `self` to the power of zero always returns 1.
#[doc = concat!("assert_eq!(3_", stringify!($SelfT), ".strict_pow(0), 1);")]
///
/// // 1 to the power of any `exp` always returns 1.
#[doc = concat!("assert_eq!(1_", stringify!($SelfT), ".strict_pow(2), 1);")]
///
/// // any `self` to the power of one always returns `self`.
#[doc = concat!("assert_eq!(3_", stringify!($SelfT), ".strict_pow(1), 3);")]
///
/// // 0 to the power of any `exp` always returns 0.
#[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".strict_pow(3), 0);")]
/// ```
///
/// The following panics because of overflow:
Expand Down Expand Up @@ -2272,6 +2298,19 @@ macro_rules! uint_impl {
/// ```
#[doc = concat!("assert_eq!(4", stringify!($SelfT), ".saturating_pow(3), 64);")]
#[doc = concat!("assert_eq!(", stringify!($SelfT), "::MAX.saturating_pow(2), ", stringify!($SelfT), "::MAX);")]
///
/// // Special cases:
/// // any `self` to the power of zero always returns 1.
#[doc = concat!("assert_eq!(3_", stringify!($SelfT), ".saturating_pow(0), 1);")]
///
/// // 1 to the power of any `exp` always returns 1.
#[doc = concat!("assert_eq!(1_", stringify!($SelfT), ".saturating_pow(2), 1);")]
///
/// // any `self` to the power of one always returns `self`.
#[doc = concat!("assert_eq!(3_", stringify!($SelfT), ".saturating_pow(1), 3);")]
///
/// // 0 to the power of any `exp` always returns 0.
#[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".saturating_pow(3), 0);")]
/// ```
#[stable(feature = "no_panic_pow", since = "1.34.0")]
#[rustc_const_stable(feature = "const_int_pow", since = "1.50.0")]
Expand Down Expand Up @@ -2580,6 +2619,19 @@ macro_rules! uint_impl {
/// ```
#[doc = concat!("assert_eq!(3", stringify!($SelfT), ".wrapping_pow(5), 243);")]
/// assert_eq!(3u8.wrapping_pow(6), 217);
///
/// // Special cases:
/// // any `self` to the power of zero always returns 1.
#[doc = concat!("assert_eq!(3_", stringify!($SelfT), ".wrapping_pow(0), 1);")]
///
/// // 1 to the power of any `exp` always returns 1.
#[doc = concat!("assert_eq!(1_", stringify!($SelfT), ".wrapping_pow(2), 1);")]
///
/// // any `self` to the power of one always returns `self`.
#[doc = concat!("assert_eq!(3_", stringify!($SelfT), ".wrapping_pow(1), 3);")]
///
/// // 0 to the power of any `exp` always returns 0.
#[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".wrapping_pow(3), 0);")]
/// ```
#[stable(feature = "no_panic_pow", since = "1.34.0")]
#[rustc_const_stable(feature = "const_int_pow", since = "1.50.0")]
Expand Down Expand Up @@ -3255,6 +3307,19 @@ macro_rules! uint_impl {
/// ```
#[doc = concat!("assert_eq!(3", stringify!($SelfT), ".overflowing_pow(5), (243, false));")]
/// assert_eq!(3u8.overflowing_pow(6), (217, true));
///
/// // Special cases:
/// // any `self` to the power of zero always returns 1.
#[doc = concat!("assert_eq!(3_", stringify!($SelfT), ".overflowing_pow(0), (1, false));")]
///
/// // 1 to the power of any `exp` always returns 1.
#[doc = concat!("assert_eq!(1_", stringify!($SelfT), ".overflowing_pow(2), (1, false));")]
///
/// // any `self` to the power of one always returns `self`.
#[doc = concat!("assert_eq!(3_", stringify!($SelfT), ".overflowing_pow(1), (3, false));")]
///
/// // 0 to the power of any `exp` always returns 0.
#[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".overflowing_pow(3), (0, false));")]
/// ```
#[stable(feature = "no_panic_pow", since = "1.34.0")]
#[rustc_const_stable(feature = "const_int_pow", since = "1.50.0")]
Expand Down Expand Up @@ -3295,6 +3360,19 @@ macro_rules! uint_impl {
///
/// ```
#[doc = concat!("assert_eq!(2", stringify!($SelfT), ".pow(5), 32);")]
///
/// // Special cases:
/// // any `self` to the power of zero always returns 1.
#[doc = concat!("assert_eq!(3_", stringify!($SelfT), ".pow(0), 1);")]
///
/// // 1 to the power of any `exp` always returns 1.
#[doc = concat!("assert_eq!(1_", stringify!($SelfT), ".pow(2), 1);")]
///
/// // any `self` to the power of one always returns `self`.
#[doc = concat!("assert_eq!(3_", stringify!($SelfT), ".pow(1), 3);")]
///
/// // 0 to the power of any `exp` always returns 0.
#[doc = concat!("assert_eq!(0_", stringify!($SelfT), ".pow(3), 0);")]
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_const_stable(feature = "const_int_pow", since = "1.50.0")]
Expand Down
62 changes: 60 additions & 2 deletions library/std/src/num/f128.rs
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Expand Up @@ -35,8 +35,66 @@ impl f128 {
/// let abs_difference = (x.powf(2.0) - (x * x)).abs();
/// assert!(abs_difference <= f128::EPSILON);
///
/// assert_eq!(f128::powf(1.0, f128::NAN), 1.0);
/// assert_eq!(f128::powf(f128::NAN, 0.0), 1.0);
/// // Special cases:
/// // pow(x, ±0) = 1 for any x
/// assert_eq!(f128::powf(3.0, 0.0), 1.0);
///
/// // pow(1, y) = 1 for any y
/// assert_eq!(f128::powf(1.0, 2.0), 1.0);
///
/// // pow(x, 1) = x for any x
/// assert_eq!(f128::powf(3.0, 1.0), 3.0);
///
/// // pow(NaN, y) = NaN
/// assert!(f128::powf(f128::NAN, 2.0).is_nan());
///
/// // pow(x, NaN) = NaN
/// assert!(f128::powf(2.0, f128::NAN).is_nan());
///
/// // pow(±0, y) = ±Inf for y an odd integer < 0
/// assert_eq!(f128::powf(0.0, -3.0), f128::INFINITY);
///
/// // pow(±0, -Inf) = +Inf
/// assert_eq!(f128::powf(0.0, f128::NEG_INFINITY), f128::INFINITY);
///
/// // pow(±0, +Inf) = +0
/// assert_eq!(f128::powf(0.0, f128::INFINITY), 0.0);
///
/// // pow(±0, y) = +Inf for finite y < 0 and not an odd integer
/// assert_eq!(f128::powf(0.0, -2.0), f128::INFINITY);
///
/// // pow(±0, y) = ±0 for y an odd integer > 0
/// assert_eq!(f128::powf(-0.0, 3.0), -0.0);
///
/// // pow(±0, y) = +0 for finite y > 0 and not an odd integer
/// assert_eq!(f128::powf(0.0, 2.0), 0.0);
///
/// // pow(-1, ±Inf) = 1
/// assert_eq!(f128::powf(-1.0, f128::INFINITY), 1.0);
///
/// // pow(x, +Inf) = +Inf for |x| > 1
/// assert_eq!(f128::powf(2.0, f128::INFINITY), f128::INFINITY);
///
/// // pow(x, -Inf) = +0 for |x| > 1
/// assert_eq!(f128::powf(2.0, f128::NEG_INFINITY), 0.0);
///
/// // pow(x, +Inf) = +0 for |x| < 1
/// assert_eq!(f128::powf(0.5, f128::INFINITY), 0.0);
///
/// // pow(x, -Inf) = +Inf for |x| < 1
/// assert_eq!(f128::powf(0.5, f128::NEG_INFINITY), f128::INFINITY);
///
/// // pow(+Inf, y) = +Inf for y > 0
/// assert_eq!(f128::powf(f128::INFINITY, 2.0), f128::INFINITY);
///
/// // pow(+Inf, y) = +0 for y < 0
/// assert_eq!(f128::powf(f128::INFINITY, -2.0), 0.0);
///
/// // pow(-Inf, y) = pow(-0, -y)
/// assert_eq!(f128::powf(f128::NEG_INFINITY, 2.0), f128::powf(-0.0, -2.0));
///
/// // pow(x, y) = NaN for finite x < 0 and finite non-integer y
/// assert!(f128::powf(-2.0, 0.5).is_nan());
/// # }
/// ```
#[inline]
Expand Down
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