is_nan

is_nan - Whether a value is a number

bool is_nan( float $x )

is_nan() checks whether x is 'not a number', like the result of acos(1.01).

Parameters:

x - The number to process. It can be a scalar or an array.

Return Value:

true or false depending on whether x is NAN. If x is an array, the return value will also be an array.

Version

1.0 and above.