Question

I want to check if a floating point value is “nearly” a multiple of 32. E.g. 64.1 is “nearly” divisible by 32, and so is 63.9.

Right now I’m doing this:

#define NEARLY_DIVISIBLE 0.1f
float offset = fmodf( val, 32.0f ) ;
if( offset < NEARLY_DIVISIBLE )
{
    // its near from above
}
// if it was 63.9, then the remainder would be large, so add some then and check again
else if( fmodf( val + 2*NEARLY_DIVISIBLE, 32.0f ) < NEARLY_DIVISIBLE )
{
    // its near from below
}

Got a better way to do this?

Answer 1

well, you could cut out the second fmodf by just subtracting 32 one more time to get the mod from below.

  if( offset < NEARLY_DIVISIBLE )
   {
       // it's near from above
   }
   else if( offset-32.0f>-1*NEARLY_DIVISIBLE)
   {
       // it's near from below
   }