fmod
    (PHP 4 >= 4.2.0)
fmod -- Returns the floating point remainder (modulo) of the division
    of the arguments
Description
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.
    
| Esempio 1. Using fmod() | $x = 5.7;
$y = 1.3;
$r = fmod($x, $y);
// $r equals 0.5, because 4 * 1.3 + 0.5 = 5.7 | 
 |