PHP acos() Function
Definition
The acos() function calculates the arc cosine value,
essentially reversing the operation of cos().
Syntax
PHP acos() Function has the following format.
float acos ( float num )Parameter
| Parameter | Description |
|---|---|
| num | Required. A number in range -1 to 1 |
Return
acos(-1) returns the value of Pi.
The return value is in radians, you should use the
rad2deg() to convert radians to degrees.
PHP acos() function returns NAN if number is not in the range -1 to 1.
Example
Calculate the arc cosine value
<?php/* w w w . ja v a 2s . co m*/
$acos1 = acos(0.4346);
print($acos1);
print "\n";
$acos2 = acos(cos(80));
print($acos2);
print "\n";
echo(acos(0.64) . "\n");
echo(acos(-0.4) . "\n");
echo(acos(0) . "\n");
echo(acos(-1) . "\n");
echo(acos(1) . "\n");
echo(acos(2));
?>
The code above generates the following result.
