PHP Math Functions (is_nan, pow, sqrt, exp, log, log10, log1p, max, min, getrandmax, rand, mt_rand)
11. is_nan() : This function takes any value as argument and checks whether a value is number or not. It returns TRUE (1) if the specified value is 'not a number', otherwise it returns FALSE/NOTHING. Syntax : is_nan(value); Example : C/C++ Code <?php echo is_nan(234) . "\n"; echo is_nan(asin(1.1)) ; ?> Output : 1 Not