Simpson's Rule

A handy function for numerically integrating a function via simpson's rule. Here's an example: ` var simpsons = require('simpsons-rule');

var F = function(x) { return 2 * x; };

var result = simpsons(F, 0, 1); // integrate from 0 to 1. Should be close to 0.5

// Or provide a step count result = simpsons(F, 0, 1, 1000); `