C standard library have: isgreater,isgreaterequal,isless,islessequal,islessgreater, isunordered.
And why doesn’t the C standard library have isequal? It should be easy to implement like that:

bool isequal(float x, float y)
{
    return !isunordered(x, y) && isgreaterequal(x, y) && !isgreater(x, y);
}