Add sin demo

Sin demo approximates the sin function using Smooth.js and prints out
the error of the approximation

Author: Spencer Cohen

sindemo.coffee

@@ -0,0 +1,28 @@
+###
+sindemo
+
+Sample and cubic interpolate the sin function, then print out max and average error.
+###
+
+{Smooth} = require './Smooth'
+
+s = (Math.sin 2*Math.PI*x for x in [0...1] by 1/8)
+
+
+#Scale the function
+smooth_sin = ((f) ->
+	scaleVal = 0.5*s.length/Math.PI
+	return (x) -> f x*scaleVal
+) Smooth s, method:Smooth.METHOD_CUBIC, clip:Smooth.CLIP_PERIODIC
+
+totalError = 0
+count = 0
+maxError = 0
+for x in [-10..10] by .001
+	error = Math.abs Math.sin(x) - smooth_sin(x)
+	maxError = Math.max error, maxError
+	totalError += error
+	count++
+
+console.log "Max Error:\t #{(100*maxError).toFixed(10)}%"
+console.log "Average Error:\t #{(100*totalError/count).toFixed(10)}%"