source: Dev/trunk/src/client/dojox/math/round.js

// AMD-ID "dojox/math/round"
define(["dojo", "dojox"], function(dojo, dojox) {

        dojo.getObject("math.round", true, dojox);
        dojo.experimental("dojox.math.round");

        dojox.math.round = function(/*Number*/value, /*Number?*/places, /*Number?*/increment){
                // summary:
                //              Similar to dojo.number.round, but compensates for binary floating point artifacts
                // description:
                //              Rounds to the nearest value with the given number of decimal places, away from zero if equal,
                //              similar to Number.toFixed().  Rounding can be done by fractional increments also.
                //              Makes minor adjustments to accommodate for precision errors due to binary floating point representation
                //              of Javascript Numbers.  See http://speleotrove.com/decimal/decifaq.html for more information.
                //              Because of this adjustment, the rounding may not be mathematically correct for full precision
                //              floating point values.  The calculations assume 14 significant figures, so the accuracy will
                //              be limited to a certain number of decimal places preserved will vary with the magnitude of
                //              the input.  This is not a substitute for decimal arithmetic.
                // value:
                //              The number to round
                // places:
                //              The number of decimal places where rounding takes place.  Defaults to 0 for whole rounding.
                //              Must be non-negative.
                // increment:
                //              Rounds next place to nearest value of increment/10.  10 by default.
                // example:
                //      |       >>> 4.8-(1.1+2.2)
                //      |       1.4999999999999996
                //      |       >>> Math.round(4.8-(1.1+2.2))
                //      |       1
                //      |       >>> dojox.math.round(4.8-(1.1+2.2))
                //      |       2
                //      |       >>> ((4.8-(1.1+2.2))/100)
                //      |       0.014999999999999996
                //      |       >>> ((4.8-(1.1+2.2))/100).toFixed(2)
                //      |       "0.01"
                //      |       >>> dojox.math.round((4.8-(1.1+2.2))/100,2)
                //      |       0.02
                //      |       >>> dojox.math.round(10.71, 0, 2.5)
                //      |       10.75
                //      |       >>> dojo.number.round(162.295, 2)
                //      |       162.29
                //      |       >>> dojox.math.round(162.295, 2)
                //      |       162.3
                var wholeFigs = Math.log(Math.abs(value))/Math.log(10);
                var factor = 10 / (increment || 10);
                var delta = Math.pow(10, -15 + wholeFigs);
                return (factor * (+value + (value > 0 ? delta : -delta))).toFixed(places) / factor; // Number
        }

        if((0.9).toFixed() == 0){
                // (isIE) toFixed() bug workaround: Rounding fails on IE when most significant digit
                // is just after the rounding place and is >=5
                var round = dojox.math.round;
                dojox.math.round = function(v, p, m){
                        var d = Math.pow(10, -p || 0), a = Math.abs(v);
                        if(!v || a >= d){
                                d = 0;
                        }else{
                                a /= d;
                                if(a < 0.5 || a >= 0.95){
                                        d = 0;
                                }
                        }
                        return round(v, p, m) + (v > 0 ? d : -d);
                }
        }

        return dojox.math.round;
});