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atan2
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atan2

Name

atan2 — Returns the arctangent based on an X-Y coordinate.

Synopsis

float atan2(x, y); float x: X-axis value of point float y: Y-axis value of point

Returns

Arctangent as a float

Description

This function returns the value of the arctangent of the point denoted by the x and y parameters. The return value is in radians, in the range -pi to pi (approximately -3.14 to 3.14).

Version

PHP 3 since 3.0.5, PHP 4

Example

Example 664. Calculate the arctangent of a coordinate

$tanx = -1;
$tany = 1;
echo "The arctangent of $tanx/$tany is ", atan2($tanx, $tany);

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