Math Constants recipe added from Wanted-Recipes

Author: AaronW

chapters/math/constants.textile

@@ -0,0 +1,49 @@
+---
+layout: recipe
+title: Math Constants
+chapter: Math
+---
+
+h2. Problem
+
+You need to use common mathematical constants like pi or e.
+
+h2. Solution
+
+Use Javascript's Math object to provide commonly needed mathematical constants.
+
+{% highlight coffeescript %}
+Math.PI
+# => 3.141592653589793
+
+# Note: Capitalization matters! This produces no output, it's undefined.
+Math.Pi
+# => 
+
+Math.E
+# => 2.718281828459045
+
+Math.SQRT2
+# => 1.4142135623730951
+
+Math.SQRT1_2
+# => 0.7071067811865476
+
+# Natural log of 2. ln(2)
+Math.LN2
+# => 0.6931471805599453
+
+Math.LN10
+# => 2.302585092994046
+
+Math.LOG2E
+# => 1.4426950408889634
+
+Math.LOG10E
+# => 0.4342944819032518
+
+{% endhighlight %}
+
+h2. Discussion
+
+For another example of how a math constant is used in a real world problem, refer to the <a href="http://coffeescriptcookbook.com/chapters/math/radians-degrees">'Converting Radians and Degrees'</a> section of this Math chapter.