These macros are from geo_decls.h:
#define EPSILON 1.0E-06
#ifdef EPSILON
#define FPzero(A) (fabs(A) <= EPSILON)
#define FPeq(A,B) (fabs((A) - (B)) <=
EPSILON)
#define FPne(A,B) (fabs((A) - (B)) >
EPSILON)
#define FPlt(A,B) ((B) - (A) > EPSILON)
#define FPle(A,B) ((A) - (B) <= EPSILON)
#define FPgt(A,B) ((A) - (B) > EPSILON)
#define FPge(A,B) ((B) - (A) <= EPSILON)
#else
#define FPzero(A) ((A) == 0)
#define FPeq(A,B) ((A) == (B))
#define FPne(A,B) ((A) != (B))
#define FPlt(A,B) ((A) < (B))
#define FPle(A,B) ((A) <= (B))
#define FPgt(A,B) ((A) > (B))
#define FPge(A,B) ((A) >= (B))
#endif
But to compare floating point, those are simply wrong. If the values
are both very small or both very large, the method fails.
Here is a more reliable way to make a comparison:
#include <float.h>
double double_compare(double d1, double d2)
{ if (d1 > d2) if ((d1 - d2) < fabs(d1 * DBL_EPSILON)) return 0; else return 1; if
(d1< d2) if ((d2 - d1) < fabs(d2 * DBL_EPSILON)) return 0; else return -1; return 0;
}
float float_compare(float d1, float d2)
{ if (d1 > d2) if ((d1 - d2) < fabs(d1 * FLT_EPSILON)) return 0; else return 1; if
(d1< d2) if ((d2 - d1) < fabs(d2 * FLT_EPSILON)) return 0; else return -1; return 0;
}
All the macros can then be defined in terms of the comparison function.
It's not perfect either, but at least it is better.
