Add the golden ratio φ

CHANGELOG.md

@@ -9,6 +9,7 @@ Breaking changes:
 
 New features:
 - Added `imul` (#18)
+- Added the golden ratio `phi` (#29)
 
 Bugfixes:
 

src/Math.js

@@ -98,6 +98,8 @@ exports.pi = Math.PI;
 
 exports.tau = 2 * Math.PI;
 
+exports.phi = (1 + Math.sqrt(5)) / 2;
+
 exports.sqrt1_2 = Math.SQRT1_2;
 
 exports.sqrt2 = Math.SQRT2;

src/Math.purs

@@ -93,6 +93,10 @@ foreign import pi :: Number
 -- | The ratio of the circumference of a circle to its radius, around 6.283185.
 foreign import tau :: Number
 
+-- | The golden ratio, *φ*, around 1.61803. Two quantities `a` and `b` are said
+-- | to be in the *golden ratio φ* if `(a + b) / a = a / b = φ`.
+foreign import phi :: Number
+
 -- | The Square root of one half, around 0.707107.
 foreign import sqrt1_2 :: Number