20 lines
481 B
JavaScript
20 lines
481 B
JavaScript
function gamma(x){
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var p = [0.99999999999980993, 676.5203681218851, -1259.1392167224028,
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771.32342877765313, -176.61502916214059, 12.507343278686905,
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-0.13857109526572012, 9.9843695780195716e-6, 1.5056327351493116e-7];
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var g = 7;
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if(x < 0.5){
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return Math.PI / (Math.sin(Math.PI * x)*gamma(1-x));
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}
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x -= 1;
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var a = p[0];
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var t = x+g+0.5;
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for(var i = 1; i < p.length; i++){
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a += p[i]/(x+i);
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}
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return Math.sqrt(2*Math.PI)*Math.pow(t, x+0.5)*Math.exp(-t)*a;
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}
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