[Lcms-user] Floating point equality comparisons

[Ethan H. <EH...@dr...>]

Several of the conversion routines in cmspcs.c perform explicit comparisons
of double values to 0. Depending on the compiler used and the optimization
parameters, these comparisons can be unreliable. A floating point number may
not be *exactly* 0 - or any other specific number for that matter - although
that was the intent of the program and/or programmer.



Suggested changes:

26a27,28
> #include <float.h>
>
 
183c185
<        if (xyz -> X == 0 && xyz -> Y == 0 && xyz -> Z == 0)
---
>        if (fabs(xyz -> X) <= DBL_EPSILON && fabs(xyz -> Y) <= DBL_EPSILON
&& fabs(xyz -> Z) <= DBL_EPSILON)

296c298
<        if (L==0.0) {
---
>        if (fabs(L) <= DBL_EPSILON) {

480c482
<     if (a == 0 && b == 0)
---
>     if (fabs(a) <= DBL_EPSILON && fabs(b) <= DBL_EPSILON)