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Fix float NaN positive/negative assumptions #315

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Merged
merged 3 commits into from
Jul 10, 2017
Merged

Fix float NaN positive/negative assumptions #315

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f0fa65a
Fix float NaN pos/neg assumptions
PlasmaPower Jul 8, 2017
aaa4ab3
Clarify what "newer versions of Rust" applies to
PlasmaPower Jul 8, 2017
426034b
Switch doctests to match functions
PlasmaPower Jul 9, 2017
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16 changes: 7 additions & 9 deletions traits/src/float.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -323,8 +323,8 @@ pub trait Float
/// ```
fn signum(self) -> Self;

/// Returns `true` if `self` is positive, including `+0.0` and
/// `Float::infinity()`.
/// Returns `true` if `self` is positive, including `+0.0`,
/// `Float::infinity()`, and `f64::NAN` with newer versions of Rust.
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Any ideas on how to make this less confusing? Right now it's not clear what "newer versions of Rust" applies to.

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NVM ".., and with newer versions of Rust f64::NAN" works.

///
/// ```
/// use num_traits::Float;
Expand All @@ -337,27 +337,25 @@ pub trait Float
///
/// assert!(f.is_sign_positive());
/// assert!(!g.is_sign_positive());
/// // Requires both tests to determine if is `NaN`
/// assert!(!nan.is_sign_positive() && !nan.is_sign_negative());
/// assert!(!nan.is_sign_negative());
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Hmm, we should be testing fn is_sign_positive() here, but I realize older rust won't return true. Perhaps this one should check !neg_nan.is_sign_positive().

/// ```
fn is_sign_positive(self) -> bool;

/// Returns `true` if `self` is negative, including `-0.0` and
/// `Float::neg_infinity()`.
/// Returns `true` if `self` is negative, including `-0.0`,
/// `Float::neg_infinity()`, and `-f64::NAN` with newer versions of Rust.
///
/// ```
/// use num_traits::Float;
/// use std::f64;
///
/// let nan = f64::NAN;
/// let neg_nan: f64 = -f64::NAN;
///
/// let f = 7.0;
/// let g = -7.0;
///
/// assert!(!f.is_sign_negative());
/// assert!(g.is_sign_negative());
/// // Requires both tests to determine if is `NaN`.
/// assert!(!nan.is_sign_positive() && !nan.is_sign_negative());
/// assert!(!neg_nan.is_sign_positive());
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And this doctest should have the !nan.is_sign_negative().

/// ```
fn is_sign_negative(self) -> bool;

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