Square it, cube it (but you can’t cut a tin can with it). Raise any number to any power.

If the result can be expressed as an integer, it will be. Otherwise, it will be a float. If the result is too large for your system (32 bits can only store so much), the special value INF will be returned.

$res = pow(4, 2);      // 16
$res = pow(4, 200);    // 2.58224987809E+120
$res = pow(4, 200000); // INF
$res = pow(-4, 2);     // 16
$res = pow(-4, 3);     // -64
$res = pow(7.3, 2);    // 53.29

A factional exponent is calculating the root. For example, an exponent of .5 means square root. [see yesterday's entry on sqrt()]

A negative exponent means do the calculation then invert the result. So, 5 to the power of -2 means 1 over (5 to the power of 2).

$res = pow(4, -2);  // 0.0625
$res = pow(4, .5);  // 2
$res = pow(4, -.5); // 0.5
$res = pow(-4, .5); // NAN