Merge branch 'float_to_neg_exp' of git://github.com/WaffleLapkin/type…

…num into WaffleLapkin-float_to_neg_exp

CHANGELOG.md

@@ -11,6 +11,8 @@ version.
 - [changed] Allowed calling `assert_type_eq` and `assert_type` at top level.
 - [added] Marker trait `Zero` for `Z0`, `U0`, and `B0`.
 
+- [added] Implementation of `Pow` trait for f32 and f64 with negative exponent
+
 ### 1.12.0 (2020-04-13)
 - [added] Feature `force_unix_path_separator` to support building without Cargo.
 - [added] Greatest common divisor operator `Gcd` with alias `Gcf`.

src/type_operators.rs

@@ -172,6 +172,14 @@ macro_rules! impl_pow_f {
                 acc
             }
         }
+
+        impl<U: Unsigned + NonZero> Pow<NInt<U>> for $t {
+            type Output = $t;
+
+            fn powi(self, _: NInt<U>) -> Self::Output {
+                <$t as Pow<PInt<U>>>::powi(self, PInt::new()).recip()
+            }
+        }
     };
 }
 
@@ -229,6 +237,7 @@ fn pow_test() {
 
     let u0 = U0::new();
     let u3 = U3::new();
+    let n3 = N3::new();
 
     macro_rules! check {
         ($x:ident) => {
@@ -244,6 +253,12 @@ fn pow_test() {
 
             assert!((<$f as Pow<P3>>::powi(*$x, p3) - $x * $x * $x).abs() < ::core::$f::EPSILON);
             assert!((<$f as Pow<U3>>::powi(*$x, u3) - $x * $x * $x).abs() < ::core::$f::EPSILON);
+
+            if *$x == 0.0 {
+                assert!(<$f as Pow<N3>>::powi(*$x, n3).is_infinite());
+            } else {
+                assert!((<$f as Pow<N3>>::powi(*$x, n3) - 1. / $x / $x / $x).abs() < ::core::$f::EPSILON);
+            }
         };
     }