Question

I have a piece of Javascript code and i am trying to convert it into C code. I have a problem to convert following line to C:

var q = (!isNaN(dLat/dPhi)) ? dLat/dPhi : Math.cos(lat1);

Can you tell me equivalent of isNan in C?
Thanks.

Answer 1

On first sight, it looks like the original author just wanted to check for dPhi being 0, so you might want to substitute that. However, if you want to translate the code verbatim, simply use the isnan macro from math.h, like this:

#include <math.h>

double q = (!isnan(dLat/dPhi)) ? dLat/dPhi : cos(lat1);