What is different about C++ math.h abs() compared to my abs()

Question

I am currently writing some glsl like vector math classes in C++, and I just implemented an abs() function like this:

template
static         


        

Answer 1

The library abs function operates on integers while you are obviously testing floats. This means that call to abs with float argument involves conversion from float to int (may be a no-op as you are using constant and compiler may do it at compile time), then INTEGER abs operation and conversion int->float. You templated function will involve operations on floats and this is probably making a difference.