Add doctests for f16 and f128 library functions where possible

library/core/src/num/f128.rs

@@ -228,6 +228,16 @@ impl f128 {
  /// the bit pattern of NaNs are conserved over arithmetic operations, the result of
  /// `is_sign_positive` on a NaN might produce an unexpected result in some cases.
  /// See [explanation of NaN as a special value](f32) for more info.
+ ///
+ /// ```
+ /// #![feature(f128)]
+ ///
+ /// let f = 7.0_f128;
+ /// let g = -7.0_f128;
+ ///
+ /// assert!(f.is_sign_positive());
+ /// assert!(!g.is_sign_positive());
+ /// ```
  #[inline]
  #[must_use]
  #[unstable(feature = "f128", issue = "116909")]
@@ -241,6 +251,16 @@ impl f128 {
  /// the bit pattern of NaNs are conserved over arithmetic operations, the result of
  /// `is_sign_negative` on a NaN might produce an unexpected result in some cases.
  /// See [explanation of NaN as a special value](f32) for more info.
+ ///
+ /// ```
+ /// #![feature(f128)]
+ ///
+ /// let f = 7.0_f128;
+ /// let g = -7.0_f128;
+ ///
+ /// assert!(!f.is_sign_negative());
+ /// assert!(g.is_sign_negative());
+ /// ```
  #[inline]
  #[must_use]
  #[unstable(feature = "f128", issue = "116909")]

library/core/src/num/f16.rs

@@ -224,6 +224,16 @@ impl f16 {
  /// the bit pattern of NaNs are conserved over arithmetic operations, the result of
  /// `is_sign_positive` on a NaN might produce an unexpected result in some cases.
  /// See [explanation of NaN as a special value](f32) for more info.
+ ///
+ /// ```
+ /// #![feature(f16)]
+ ///
+ /// let f = 7.0_f16;
+ /// let g = -7.0_f16;
+ ///
+ /// assert!(f.is_sign_positive());
+ /// assert!(!g.is_sign_positive());
+ /// ```
  #[inline]
  #[must_use]
  #[unstable(feature = "f16", issue = "116909")]
@@ -237,6 +247,16 @@ impl f16 {
  /// the bit pattern of NaNs are conserved over arithmetic operations, the result of
  /// `is_sign_negative` on a NaN might produce an unexpected result in some cases.
  /// See [explanation of NaN as a special value](f32) for more info.
+ ///
+ /// ```
+ /// #![feature(f16)]
+ ///
+ /// let f = 7.0_f16;
+ /// let g = -7.0_f16;
+ ///
+ /// assert!(!f.is_sign_negative());
+ /// assert!(g.is_sign_negative());
+ /// ```
  #[inline]
  #[must_use]
  #[unstable(feature = "f16", issue = "116909")]

library/core/src/num/f64.rs

@@ -1111,7 +1111,6 @@ impl f64 {
  /// ```
  /// assert!((1f64).to_bits() != 1f64 as u64); // to_bits() is not casting!
  /// assert_eq!((12.5f64).to_bits(), 0x4029000000000000);
- ///
  /// ```
  #[must_use = "this returns the result of the operation, \
  without modifying the original"]