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Changed calculation of math.sqrt to avoid numerical problems when re < 0

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This commit is contained in:
Pavel Panchekha 2014-08-11 17:30:23 -07:00
parent 24cdfb90a7
commit 2ef53ce069
1 changed files with 20 additions and 9 deletions
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29
lib/function/arithmetic/sqrt.js
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@ -52,17 +52,28 @@ module.exports = function (math) {
if (isComplex(x)) {
var r = Math.sqrt(x.re * x.re + x.im * x.im);
if (x.im >= 0) {
return new Complex(
0.5 * Math.sqrt(2.0 * (r + x.re)),
0.5 * Math.sqrt(2.0 * (r - x.re))
);
var re, im;
if (x.re >= 0) {
re = 0.5 * Math.sqrt(2.0 * (r + x.re));
}
else {
return new Complex(
0.5 * Math.sqrt(2.0 * (r + x.re)),
-0.5 * Math.sqrt(2.0 * (r - x.re))
);
re = Math.abs(x.im) / Math.sqrt(2 * (r - x.re));
}
if (x.re <= 0) {
im = 0.5 * Math.sqrt(2.0 * (r - x.re));
}
else {
im = Math.abs(x.im) / Math.sqrt(2 * (r + x.re));
}
if (x.im >= 0) {
return new Complex(re, im);
}
else {
return new Complex(re, -im);
}
}