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Fixed floating point zero condition in equation solver

This commit is contained in:
Viktor Chlumský 2019-11-16 11:35:40 +01:00
parent b79eacb9ae
commit b1c9f2825d
1 changed files with 14 additions and 6 deletions
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20
core/equation-solver.cpp
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@ -4,13 +4,17 @@
#define _USE_MATH_DEFINES
#include <cmath>
#define TOO_LARGE_RATIO 1e12
namespace msdfgen {
int solveQuadratic(double x[2], double a, double b, double c) {
if (fabs(a) < 1e-14) {
if (fabs(b) < 1e-14) {
// a = 0 -> linear equation
if (a == 0 || fabs(b)+fabs(c) > TOO_LARGE_RATIO*fabs(a)) {
// a, b = 0 -> no solution
if (b == 0 || fabs(c) > TOO_LARGE_RATIO*fabs(b)) {
if (c == 0)
return -1;
return -1; // 0 = 0
return 0;
}
x[0] = -c/b;
@ -61,9 +65,13 @@ static int solveCubicNormed(double x[3], double a, double b, double c) {
}
int solveCubic(double x[3], double a, double b, double c, double d) {
if (fabs(a) < 1e-14)
return solveQuadratic(x, b, c, d);
return solveCubicNormed(x, b/a, c/a, d/a);
if (a != 0) {
double bn = b/a, cn = c/a, dn = d/a;
// Check that a isn't "almost zero"
if (fabs(bn) < TOO_LARGE_RATIO && fabs(cn) < TOO_LARGE_RATIO && fabs(dn) < TOO_LARGE_RATIO)
return solveCubicNormed(x, bn, cn, dn);
}
return solveQuadratic(x, b, c, d);
}
}