Happy Coders

The atan() function in PHP returns the inverse tangent (arc tangent) of a number.
It outputs the angle in radians whose tangent is the given value.
The result lies between -π/2 and +π/2.
You can use it for trigonometric calculations, slope angles, or rotations.
Use rad2deg() to convert the result into degrees if needed.

Syntax

atan(float $num): float

• $num: Any real number
• Returns: Arc tangent of the number in radians
• Range of result: from -π/2 to +π/2

File Name: atan-example.php

<?php
echo atan(1);      // ➤ 0.78539816339745 (π/4 radians)
echo "\n";
echo atan(0);      // ➤ 0
echo "\n";
echo atan(-1);     // ➤ -0.78539816339745 (-π/4 radians)
?>

Convert Radians to Degrees

$angle = atan(1);
$degrees = rad2deg($angle);  // ➤ 45
echo $degrees;

Use Cases