Isnan - Analog Devices VISUALDSP++ 3.5 Manual

isnan

test for not-a-number (NAN)
Synopsis
#include <math.h>
int isnanf(float x);
int isnan(double x);
Description
The function returns a zero if the argument is not set to an IEEE
isnan
(Not a Number); otherwise, the function will return a non-zero value.
NaN
Error Conditions
The function does not return or set any error conditions.
isnan
Example
#include <stdio.h>
#include <math.h>
static int fail=0;
main(){
/* test int isnan(double) */
union {
double d; float f; unsigned long l;
} u;
#ifdef __DOUBLES_ARE_FLOATS__
u.l=0xFF800000L; if ( isnan(u.d)!=0 ) fail++;
u.l=0xFF800001L; if ( isnan(u.d)==0 ) fail++;
u.l=0x7F800000L; if ( isnan(u.d)!=0 ) fail++;
VisualDSP++ 3.5 C/C++ Compiler and Library Manual
for ADSP-219x DSPs
C/C++ Run-Time Library
3-79