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Further cleanups in Numerical.solveQuadratic()

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This commit is contained in:
Jürg Lehni 2016-07-09 01:10:55 +02:00
parent 02658c9e74
commit 7e3d18f5d4
1 changed files with 9 additions and 11 deletions
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20
src/util/Numerical.js
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@ -255,31 +255,29 @@ var Numerical = new function() {
eMin = min - EPSILON,
eMax = max + EPSILON,
x1, x2 = Infinity,
B = b,
D, E;
// a, b, c are expected to be the coefficients of the equation:
// Ax² - 2Bx + C == 0, so we take b = -B/2:
b *= -0.5;
D = getDiscriminant(a, b, c);
// a, b, c are expected to be the coefficients of the equation:
// Ax² - 2Bx + C == 0, so we take B = -b/2:
B = b * -0.5,
D = getDiscriminant(a, B, c);
// If the discriminant is very small, we can try to pre-condition
// the coefficients, so that we may get better accuracy
if (D && abs(D) < MACHINE_EPSILON) {
// Normalize coefficients.
var f = getNormalizationFactor(abs(a) + abs(b) + abs(c));
var f = getNormalizationFactor(abs(a) + abs(B) + abs(c));
a *= f;
b *= f;
c *= f;
B *= f;
D = getDiscriminant(a, b, c);
D = getDiscriminant(a, B, c);
}
if (abs(a) < EPSILON) {
// This could just be a linear equation
if (abs(B) < EPSILON)
if (abs(b) < EPSILON)
return abs(c) < EPSILON ? -1 : 0;
x1 = -c / B;
x1 = -c / b;
} else if (D >= -MACHINE_EPSILON) { // No real roots if D < 0
var Q = D < 0 ? 0 : sqrt(D),
R = b + (b < 0 ? -Q : Q);
R = B + (B < 0 ? -Q : Q);
// Try to minimize floating point noise.
if (R === 0) {
x1 = c / a;