[Vxl-maintainers] vnl_math.cxx

[Brad K. <bra...@ki...>]

Hello,

I've run into problems recently with vnl_math_isnan, vnl_math_isinf, and
vnl_math_isfinite on several platforms.  These functions use the isnan,
isinf, and isfinite macros defined by <math.h> in only some cases.  The
hand-written implementations are working on fewer and fewer platforms as
long double gets bigger.

I would like to use VXL_C_MATH_HAS_FINITE to switch on/off using the
isnan, isinf, and isfinite macros without other checks.  Does anyone know
if this is safe everywhere?  There seems to be alot of preprocessor logic
to support older platforms.  I'm curious as to the history of these
implementations because I do not want to blow away years of accumulated
knowledge in trying to fix these functions.  Can anyone shed light on
this?

Thanks,
-Brad