PHP Functions Essential Reference

atan

float atan(float x) 

Returns the calculated arctangent for the given argument.

Returns:

Arctangent as a float

Description:

atan() calculates the arctangent for a single value.

Version:

PHP 3, PHP 4

See also:

acos() 
asin() 
atan2() 
cos() 
sin() 
tan() 

Example:

Calculate the arctangent for a value

$tan = 10.0; echo "The arctangent of $tan is ", atan($tan);