isinf,  isnan,  finite - test for infinity or not-a-number
       (NaN)


SYNOPSIS

       #include <math.h>

       int isinf(double value);

       int isnan(double value);

       int finite(double value);


DESCRIPTION

       The isinf() function returns -1 if value represents  nega­
       tive  infinity,  1  if value represents positive infinity,
       and 0 otherwise.

       The isnan() function returns a non-zero value if value  is
       "not-a-number" (NaN), and 0 otherwise.

       The finite() function returns a non-zero value if value is
       neither infinite nor a "not-a-number" (NaN) value,  and  0
       otherwise.


CONFORMING TO

       BSD 4.3