Definition and Usage
Most trigonometric functions like sin, cos, tan etc require angle argument in radians. The deg2rad() function proves useful in conversion of degrees to radians.
This function returns a float number such that number=deg2rad(x) where is angle in degrees. angle in radian = angle in deg *180/pi
For example deg2rad(30) is equal to 0.5235987755983 radians
Syntax
deg2rad ( float $number ) : float
Parameters
| Sr.No | Parameter & Description |
|---|---|
| 1 | number A float number reprsenting angle in degrees |
Return Values
PHP deg2rad() function returns a float number that represents angle in radians.
PHP Version
This function is available in PHP versions 4.x, PHP 5.x as well as PHP 7.x.
Example
Following example calculates radian equivalent of 30 degrees −
<?php
$arg=30;
$val=deg2rad($arg);
echo "deg2rad(" . $arg . ") = " . $val;
?>Output
This will produce following result −
deg2rad(30) = 0.5235987755983
Example
Following example converts 180 deg in radians. We can confirm the result by comparing with value of M_PI. −
<?php
$arg=180;
$val=deg2rad($arg);
echo "deg2rad(" . $arg . ") = " . $val . "\n";
echo "pi in radians = ". M_PI;
?>Output
This will produce following result −
deg2rad(180) = 3.1415926535898 pi in radians = 3.1415926535898
Example
Non numeric argument produces error: −
<?php
$arg="Hello";
$val=deg2rad($arg);
echo "deg2rad(" . $arg . ") = " . $val;
?>Output
This will produce following result −
PHP Warning: deg2rad() expects parameter 1 to be float, string given
Example
The argument number can be a binary, octal or hexadecimal decimal number. Following example converts 0x2d angle (equal to 45 degrees) to radians.
<?php
$arg=0x2d;
$val=deg2rad($arg);
echo "deg2rad(" . $arg . ") = " . $val;
?>Output
This will produce following result −
deg2rad(45) = 0.78539816339745