Objective-C - float checking for nan
Solution 1:
Two ways, which are more or less equivalent:
if (slope != slope) {
// handle nan here
}
Or
#include <math.h>
...
if (isnan(slope)) {
// handle nan here
}
(man isnan will give you more information, or you can read all about it in the C standard)
Alternatively, you could detect that the denominator is zero before you do the divide (or use atan2 if you're just going to end up using atan on the slope instead of doing some other computation).
Solution 2:
Nothing is equal to NaN — including NaN itself. So check x != x.