| /* |
| Copyright (c) 2004-2005, The Dojo Foundation |
| All Rights Reserved. |
| |
| Licensed under the Academic Free License version 2.1 or above OR the |
| modified BSD license. For more information on Dojo licensing, see: |
| |
| http://dojotoolkit.org/community/licensing.shtml |
| */ |
| |
| dojo.provide("dojo.math"); |
| |
| dojo.math.degToRad = function (x) { return (x*Math.PI) / 180; } |
| dojo.math.radToDeg = function (x) { return (x*180) / Math.PI; } |
| |
| dojo.math.factorial = function (n) { |
| if(n<1){ return 0; } |
| var retVal = 1; |
| for(var i=1;i<=n;i++){ retVal *= i; } |
| return retVal; |
| } |
| |
| //The number of ways of obtaining an ordered subset of k elements from a set of n elements |
| dojo.math.permutations = function (n,k) { |
| if(n==0 || k==0) return 1; |
| return (dojo.math.factorial(n) / dojo.math.factorial(n-k)); |
| } |
| |
| //The number of ways of picking n unordered outcomes from r possibilities |
| dojo.math.combinations = function (n,r) { |
| if(n==0 || r==0) return 1; |
| return (dojo.math.factorial(n) / (dojo.math.factorial(n-r) * dojo.math.factorial(r))); |
| } |
| |
| dojo.math.bernstein = function (t,n,i) { |
| return (dojo.math.combinations(n,i) * Math.pow(t,i) * Math.pow(1-t,n-i)); |
| } |
| |
| /** |
| * Returns random numbers with a Gaussian distribution, with the mean set at |
| * 0 and the variance set at 1. |
| * |
| * @return A random number from a Gaussian distribution |
| */ |
| dojo.math.gaussianRandom = function () { |
| var k = 2; |
| do { |
| var i = 2 * Math.random() - 1; |
| var j = 2 * Math.random() - 1; |
| k = i * i + j * j; |
| } while (k >= 1); |
| k = Math.sqrt((-2 * Math.log(k)) / k); |
| return i * k; |
| } |
| |
| /** |
| * Calculates the mean of an Array of numbers. |
| * |
| * @return The mean of the numbers in the Array |
| */ |
| dojo.math.mean = function () { |
| var array = dojo.lang.isArray(arguments[0]) ? arguments[0] : arguments; |
| var mean = 0; |
| for (var i = 0; i < array.length; i++) { mean += array[i]; } |
| return mean / array.length; |
| } |
| |
| /** |
| * Extends Math.round by adding a second argument specifying the number of |
| * decimal places to round to. |
| * |
| * @param number The number to round |
| * @param places The number of decimal places to round to |
| * @return The rounded number |
| */ |
| // TODO: add support for significant figures |
| dojo.math.round = function (number, places) { |
| if (!places) { var shift = 1; } |
| else { var shift = Math.pow(10, places); } |
| return Math.round(number * shift) / shift; |
| } |
| |
| /** |
| * Calculates the standard deviation of an Array of numbers |
| * |
| * @return The standard deviation of the numbers |
| */ |
| dojo.math.sd = function () { |
| var array = dojo.lang.isArray(arguments[0]) ? arguments[0] : arguments; |
| return Math.sqrt(dojo.math.variance(array)); |
| } |
| |
| /** |
| * Calculates the variance of an Array of numbers |
| * |
| * @return The variance of the numbers |
| */ |
| dojo.math.variance = function () { |
| var array = dojo.lang.isArray(arguments[0]) ? arguments[0] : arguments; |
| var mean = 0, squares = 0; |
| for (var i = 0; i < array.length; i++) { |
| mean += array[i]; |
| squares += Math.pow(array[i], 2); |
| } |
| return (squares / array.length) |
| - Math.pow(mean / array.length, 2); |
| } |
| |
| /** |
| * Like range() in python |
| **/ |
| dojo.math.range = function(a, b, step) { |
| if(arguments.length < 2) { |
| b = a; |
| a = 0; |
| } |
| if(arguments.length < 3) { |
| step = 1; |
| } |
| |
| var range = []; |
| if(step > 0) { |
| for(var i = a; i < b; i += step) { |
| range.push(i); |
| } |
| } else if(step < 0) { |
| for(var i = a; i > b; i += step) { |
| range.push(i); |
| } |
| } else { |
| throw new Error("dojo.math.range: step must be non-zero"); |
| } |
| return range; |
| } |