teepusink - 4 months ago 34

Objective-C Question

I have a variable (

`float slope`

I am trying to do an if-else for when that happens. How can I do that?

`if (slope == nan)`

Answer

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).