scratchfoundation/paper.js
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Fix porting mistakes.

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This commit is contained in:
Jürg Lehni 2011-07-06 15:31:36 +02:00
parent 8d35aab7cd
commit 10e7cc994c
1 changed files with 7 additions and 7 deletions
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14
src/util/Numerical.js
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@ -166,24 +166,24 @@ var Numerical = new function() {
R = (2 * b * b * b - 9 * b * c + 27 * d) / 54,
Q3 = Q * Q * Q,
R2 = R * R;
if (R2 <= Q3) { // Three real roots
b /= 3; // Divide by 3 as that's required below
if (R2 < Q3) { // Three real roots
// This sqrt and division is safe, since R2 >= 0, so Q3 > R2,
// so Q3 > 0. The acos is also safe, since R2/Q3 < 1, and
// thus R/sqrt(Q3) < 1.
var theta = Math.acos(R / sqrt(Q3)),
// This sqrt is safe, since Q3 >= 0, and thus Q >= 0
v1 = -2 * sqrt(Q);
v2 = b / 3;
q = -2 * sqrt(Q);
return [
v1 * cos(theta / 3) - v2,
v1 * cos((theta + 2 * PI) / 3) - v2,
v1 * cos((theta - 2 * PI) / 3) - v2
q * cos(theta / 3) - b,
q * cos((theta + 2 * PI) / 3) - b,
q * cos((theta - 2 * PI) / 3) - b
];
} else { // One real root
var A = -Math.pow(abs(R) + sqrt(R2 - Q3), 1 / 3);
if (R < 0) A = -A;
var B = (abs(A) < tolerance) ? 0 : Q / A;
return [ (A + B) - a ];
return [ (A + B) - b ];
}
return [];
}