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PHP atan2() Function
Definition and Usage
The atan2() function calculates arc tan of two variables
atan2(y,x) returns the arc tangent of the two numbers x and y. although it is similar to atan(y)/atan(x), the signs of both x and y are used to determine the quadrant of the result. Accordingly for values of x and y atan2() is
atan(y/x) if x>0
atan(y/x)+pi if x>0
atan(y/x)-pi if x<0 and y<0
pi/2 if x=0 and y>0
-pi/2 if x=0 and y<0
0 if x=0 and y=0
This function returns angle in radians which is a float value.
Syntax
atan2 ( float $y , float $x ) : float
Parameters
| Sr.No | Parameter & Description |
|---|---|
| 1 | y dividend |
| 2 | x divisor |
Return Values
PHP atan2() function returns angle in radian which is a float number.
PHP Version
This function is available in PHP versions 4.x, PHP 5.x as well as PHP 7.x.
Example
Following example calculates atan2(1,2) −
<?php
$y=1;
$x=2;
$val=atan2($y, $x);;
echo "atan2(" . $y ."," . $x .") = " . $val;
?>Output
This will produce following result −
atan2(1,2) = 0.46364760900081
Example
Following example calculate atan2(5, -5) −
<?php
$y=5;
$x=-5;
$val=atan2($y, $x);;
echo "atan2(" . $y ."," . $x .") = " . $val;
?>Output
This will produce following result −
atan2(5,-5) = 2.3561944901923
Example
Following program computes atan2(5,0) and returns 1.570796326795 (M_PI_2) −
<?php
$y=5;
$x=0;
$val=atan2($y, $x);;
echo "atan2(" . $y ."," . $x .") = " . $val;
?>Output
This will produce following result −
atan2(5,0) = 1.5707963267949
Example
Following example computes atan2(0,0) and returns 0
<?php
$y=0;
$x=0;
$val=atan2($y, $x);;
echo "atan2(" . $y ."," . $x .") = " . $val;
?>Output
This will produce following result −
atan2(0,0) = 0
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