DESCRIPTION
The isinf() function returns -1 if value represents negative 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.
NOTE
C99 provides additional macros, such as the type-independent fpclassify(), isinf() and isnan().
"CONFORMING TO"
BSD 4.3
"SEE ALSO"
fpclassify(3)
