Fix documentation link & simplify construction

Author: rayhem

src/lib.rs

@@ -161,12 +161,11 @@ impl<T: Clone + Signed> Complex<T> {
 
 #[cfg(any(feature = "std", feature = "libm"))]
 impl<T: Float> Complex<T> {
-    /// Create a new Complex with a given phase -- `exp(i * phase)`
-    ///
-    /// [cis (mathematics)]: https://en.wikipedia.org/wiki/Cis_(mathematics)
+    /// Create a new Complex with a given phase: `exp(i * phase)`.
+    /// See [cis (mathematics)](https://en.wikipedia.org/wiki/Cis_(mathematics)).
     #[inline]
     pub fn cis(phase: T) -> Self {
-        (Self::i() * phase).exp()
+        Self::new(phase.cos(), phase.sin())
     }
 
     /// Calculate |self|