Math Trigonometric functions atan() to get arc tangent value of any radian as input in PHP

Calculate inverse tangent

atan() returns the arc tangent of a number in radians. Use atan2() when you have separate x and y components and need correct quadrant handling.

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

The examples below build from the basic call to practical variations and edge cases.

<?Php
echo atan(0); // Output is 0
echo "<br>";
echo atan(1); // Output  0.78539816339745
echo "<br>";
echo atan(-1); // -0.78539816339745
echo "<br>";
echo atan(4); // Output is 1.325817663668
echo "<br>";
echo atan(2); // Output is 1.1071487177941
echo "<br>";
echo atan(90); // Output is 1.5596856728973
?>

atan(float $num): float;

The argument is a numeric ratio. atan() returns the corresponding angle in radians. Use rad2deg() when you need degrees.

Convert the returned angle to degrees

$ratio = 1;
$angleRadians = atan($ratio);
echo rad2deg($angleRadians); // 45

Example: Calculating Angle in a Triangle

$opposite = 5;
$adjacent = 10;
$angle = atan($opposite / $adjacent);  // Result in radians
$angle_in_degrees = rad2deg($angle);
echo $angle_in_degrees;  // Output: 26.565 degrees

Example: Handling Edge Cases

echo atan(0);  // Output: 0
echo atan(-1);  // Output: -0.785398163 (negative angle)

Example: Comparing atan() and atan2()

$y = 5;
$x = 10;
echo atan($y / $x);  // Output: 0.463 radians

// Using atan2 to handle full quadrant angles
echo atan2($y, $x);  // Output: 0.463 radians (same, but handles quadrant correctly)

Explanation:
Triangle Calculation: Demonstrates a practical application for calculating angles from side lengths.
Edge Case Handling: Explains what happens when input values are zero or negative.
Comparison: Clarifies when `atan()` or `atan2()` should be used for handling angles in different quadrants.

Questions

What does the `atan()` function in PHP do?
What is the purpose of the `atan()` function in PHP?
How is the `atan()` function used to calculate the arctangent (inverse tangent) of a number?
What is the range of values returned by the `atan()` function in PHP?
Can the `atan()` function be used with both degrees and radians?
What happens if you pass an invalid argument to the `atan()` function?
How can you use the `atan()` function to calculate the angle in radians given the tangent value?
Are there any alternative ways to calculate the inverse tangent in PHP besides using the `atan()` function?
Can the `atan()` function return a complex number?
What type of value does the `atan()` function return: integer, float, or something else?

ATAN2() function
Math Functions

Subhendu Mohapatra

Author & Instructor at plus2net

I write and maintain practical tutorials on Python, PHP, SQL, JavaScript, HTML, jQuery, and web development at plus2net. The tutorials focus on clear explanations, working examples, and code that readers can test and adapt while learning.

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