62 lines
2.4 KiB
JavaScript
62 lines
2.4 KiB
JavaScript
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dojo.provide("dojox.math.round");
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dojo.experimental("dojox.math.round");
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dojox.math.round = function(/*Number*/value, /*Number?*/places, /*Number?*/increment){
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// summary:
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// Similar to dojo.number.round, but compensates for binary floating point artifacts
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// description:
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// Rounds to the nearest value with the given number of decimal places, away from zero if equal,
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// similar to Number.toFixed(). Rounding can be done by fractional increments also.
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// Makes minor adjustments to accommodate for precision errors due to binary floating point representation
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// of Javascript Numbers. See http://speleotrove.com/decimal/decifaq.html for more information.
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// Because of this adjustment, the rounding may not be mathematically correct for full precision
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// floating point values. The calculations assume 14 significant figures, so the accuracy will
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// be limited to a certain number of decimal places preserved will vary with the magnitude of
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// the input. This is not a substitute for decimal arithmetic.
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// value:
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// The number to round
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// places:
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// The number of decimal places where rounding takes place. Defaults to 0 for whole rounding.
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// Must be non-negative.
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// increment:
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// Rounds next place to nearest value of increment/10. 10 by default.
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// example:
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// >>> 4.8-(1.1+2.2)
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// 1.4999999999999996
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// >>> Math.round(4.8-(1.1+2.2))
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// 1
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// >>> dojox.math.round(4.8-(1.1+2.2))
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// 2
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// >>> ((4.8-(1.1+2.2))/100)
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// 0.014999999999999996
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// >>> ((4.8-(1.1+2.2))/100).toFixed(2)
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// "0.01"
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// >>> dojox.math.round((4.8-(1.1+2.2))/100,2)
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// 0.02
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// >>> dojox.math.round(10.71, 0, 2.5)
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// 10.75
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// >>> dojo.number.round(162.295, 2)
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// 162.29
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// >>> dojox.math.round(162.295, 2)
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// 162.3
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var wholeFigs = Math.log(Math.abs(value))/Math.log(10);
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var factor = 10 / (increment || 10);
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var delta = Math.pow(10, -15 + wholeFigs);
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return (factor * (+value + (value > 0 ? delta : -delta))).toFixed(places) / factor; // Number
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}
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if((0.9).toFixed() == 0){
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// (isIE) toFixed() bug workaround: Rounding fails on IE when most significant digit
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// is just after the rounding place and is >=5
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(function(){
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var round = dojox.math.round;
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dojox.math.round = function(v, p, m){
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var d = Math.pow(10, -p || 0), a = Math.abs(v);
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if(!v || a >= d || a * Math.pow(10, p + 1) < 5){
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d = 0;
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}
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return round(v, p, m) + (v > 0 ? d : -d);
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}
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})();
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}
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