Math Functions
PHP Manual

is_nan

Finds whether a value is not a number

Description

bool is_nan ( float $val )

Checks whether val is 'not a number', like the result of acos(1.01).

Parameters

val

The value to check

Return Values

Returns TRUE if val is 'not a number', else FALSE.

Examples

Example #1 is_nan example

<?php
// Invalid calculation, will return a 
// NaN value
$nan = acos(8);

var_dump($nan, is_nan($nan));
?>

The above example will output:

float(NAN)
bool(true)

See Also

  • is_finite
  • is_infinite