PHP is_nan() - Math Functions
What is an is_nan Function?
Explanation
The "is_nan()" function finds whether a value is not a number.
Syntax:
is_nan(x)
In the above syntax "x" is the value to check whether the given value is a number.
Example :
<?php
echo is_nan(400). "<br />";
echo is_nan(acos(8));
?>
Result::
1
In the above example the first value is "400" its a number it returns "1", since cos(8) is not a number it returns nothing.