asin

(PHP 4, PHP 5, PHP 7, PHP 8)

asin — 反正弦

说明

asin ( float $arg ) : float

返回 arg 的反正弦值，单位是弧度。asin() 是 sin() 的反函数，它的意思是在 asin() 范围里的每个值都是 a==sin(asin(a)) 。

参数

arg

待处理的参数

返回值

arg 的反正弦弧度。

参见

User Contributed Notes

rahmatjon at gmail dot com 16-Jan-2021 03:17
Hello!
Please put this example below the asin() function's description.
Thank you!

Example:
<?php
    $arg = 0.5;
    $val = asin($arg);
    echo "asin(" . $arg . ") = " . $val . " radians.<br/>";
    echo "Pi value = " . pi() . "<br/>";  
    echo "asin(" . $arg . ") = " . $val/pi()*180 . " degrees<br/>";

    $arg = 1;
    $val = asin($arg);
    echo "asin(" . $arg . ") = " . $val . " radians.<br/>";
    echo "Pi value = " . pi() . "<br/>";  
    echo "asin(" . $arg . ") = " . $val/pi()*180 . " degrees<br/>";
?>