fmod()
Returns the floating point remainder (modulo) of the division of the arguments

Syntax : float fmod ( float x, float y)
Returns the floating point remainder of dividing the dividend (x) by the divisor (y). The reminder (r) is defined as: x = i * y + r, for some integer i. If y is non-zero, r has the same sign as x and a magnitude less than the magnitude of y.