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# atan2

(PHP 3>= 3.0.5, PHP 4 , PHP 5)

atan2 -- Arc tangent of two variables

## Description

float atan2 ( float y, float x)

This function calculates the arc tangent of the two variables x and y. It is similar to calculating the arc tangent of y / x, except that the signs of both arguments are used to determine the quadrant of the result.

The function returns the result in radians, which is between -PI and PI (inclusive).

See also acos() and atan().

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