add constants in std::f16::consts

Author: tspiteri

Diff for: core/src/num/f16.rs

@@ -15,7 +15,112 @@ use crate::mem;
 
 /// Basic mathematical constants.
 #[unstable(feature = "f16", issue = "116909")]
-pub mod consts {}
+pub mod consts {
+    // FIXME: replace with mathematical constants from cmath.
+
+    /// Archimedes' constant (π)
+    #[unstable(feature = "f16", issue = "116909")]
+    pub const PI: f16 = 3.14159265358979323846264338327950288_f16;
+
+    /// The full circle constant (τ)
+    ///
+    /// Equal to 2π.
+    #[unstable(feature = "f16", issue = "116909")]
+    pub const TAU: f16 = 6.28318530717958647692528676655900577_f16;
+
+    /// The golden ratio (φ)
+    #[unstable(feature = "f16", issue = "116909")]
+    // Also, #[unstable(feature = "more_float_constants", issue = "103883")]
+    pub const PHI: f16 = 1.618033988749894848204586834365638118_f16;
+
+    /// The Euler-Mascheroni constant (γ)
+    #[unstable(feature = "f16", issue = "116909")]
+    // Also, #[unstable(feature = "more_float_constants", issue = "103883")]
+    pub const EGAMMA: f16 = 0.577215664901532860606512090082402431_f16;
+
+    /// π/2
+    #[unstable(feature = "f16", issue = "116909")]
+    pub const FRAC_PI_2: f16 = 1.57079632679489661923132169163975144_f16;
+
+    /// π/3
+    #[unstable(feature = "f16", issue = "116909")]
+    pub const FRAC_PI_3: f16 = 1.04719755119659774615421446109316763_f16;
+
+    /// π/4
+    #[unstable(feature = "f16", issue = "116909")]
+    pub const FRAC_PI_4: f16 = 0.785398163397448309615660845819875721_f16;
+
+    /// π/6
+    #[unstable(feature = "f16", issue = "116909")]
+    pub const FRAC_PI_6: f16 = 0.52359877559829887307710723054658381_f16;
+
+    /// π/8
+    #[unstable(feature = "f16", issue = "116909")]
+    pub const FRAC_PI_8: f16 = 0.39269908169872415480783042290993786_f16;
+
+    /// 1/π
+    #[unstable(feature = "f16", issue = "116909")]
+    pub const FRAC_1_PI: f16 = 0.318309886183790671537767526745028724_f16;
+
+    /// 1/sqrt(π)
+    #[unstable(feature = "f16", issue = "116909")]
+    // Also, #[unstable(feature = "more_float_constants", issue = "103883")]
+    pub const FRAC_1_SQRT_PI: f16 = 0.564189583547756286948079451560772586_f16;
+
+    /// 2/π
+    #[unstable(feature = "f16", issue = "116909")]
+    pub const FRAC_2_PI: f16 = 0.636619772367581343075535053490057448_f16;
+
+    /// 2/sqrt(π)
+    #[unstable(feature = "f16", issue = "116909")]
+    pub const FRAC_2_SQRT_PI: f16 = 1.12837916709551257389615890312154517_f16;
+
+    /// sqrt(2)
+    #[unstable(feature = "f16", issue = "116909")]
+    pub const SQRT_2: f16 = 1.41421356237309504880168872420969808_f16;
+
+    /// 1/sqrt(2)
+    #[unstable(feature = "f16", issue = "116909")]
+    pub const FRAC_1_SQRT_2: f16 = 0.707106781186547524400844362104849039_f16;
+
+    /// sqrt(3)
+    #[unstable(feature = "f16", issue = "116909")]
+    // Also, #[unstable(feature = "more_float_constants", issue = "103883")]
+    pub const SQRT_3: f16 = 1.732050807568877293527446341505872367_f16;
+
+    /// 1/sqrt(3)
+    #[unstable(feature = "f16", issue = "116909")]
+    // Also, #[unstable(feature = "more_float_constants", issue = "103883")]
+    pub const FRAC_1_SQRT_3: f16 = 0.577350269189625764509148780501957456_f16;
+
+    /// Euler's number (e)
+    #[unstable(feature = "f16", issue = "116909")]
+    pub const E: f16 = 2.71828182845904523536028747135266250_f16;
+
+    /// log<sub>2</sub>(10)
+    #[unstable(feature = "f16", issue = "116909")]
+    pub const LOG2_10: f16 = 3.32192809488736234787031942948939018_f16;
+
+    /// log<sub>2</sub>(e)
+    #[unstable(feature = "f16", issue = "116909")]
+    pub const LOG2_E: f16 = 1.44269504088896340735992468100189214_f16;
+
+    /// log<sub>10</sub>(2)
+    #[unstable(feature = "f16", issue = "116909")]
+    pub const LOG10_2: f16 = 0.301029995663981195213738894724493027_f16;
+
+    /// log<sub>10</sub>(e)
+    #[unstable(feature = "f16", issue = "116909")]
+    pub const LOG10_E: f16 = 0.434294481903251827651128918916605082_f16;
+
+    /// ln(2)
+    #[unstable(feature = "f16", issue = "116909")]
+    pub const LN_2: f16 = 0.693147180559945309417232121458176568_f16;
+
+    /// ln(10)
+    #[unstable(feature = "f16", issue = "116909")]
+    pub const LN_10: f16 = 2.30258509299404568401799145468436421_f16;
+}
 
 #[cfg(not(test))]
 impl f16 {