PHP pi() 函数

pi() 是 PHP 中的重要数学函数，用于解决数学问题。它返回 PI 的近似值。

我们可以使用 M_PI 常量作为 pi() 的结果。

语法

        float pi ( void )

示例1

<?php
echo "By using 'pi()' Function the value of PI : ".(pi());
?>

输出：

By using 'pi()' Function the value of PI : 3.1415926535898

示例2

<?php
echo "By using 'M_PI' constant the value of PI : ".M_PI_2;
    ?>

输出：

By using 'M_PI' constant the value of PI : 1.5707963267949

示例3

<?php
echo "By using 'M_PI_2' constant the value of PI : ".M_PI_2; //  pi/2 
echo "<br>"."By using 'M_PI_4' constant the value of PI : ".M_PI_4;  //  pi/4
?>

输出：

By using 'M_PI_2' constant the value of PI : 1.5707963267949
By using 'M_PI_4' constant the value of PI : 0.78539816339745

示例4

<?php
echo "By using 'M_SQRTPI' constant the value of PI : ".M_SQRTPI;   //sqrt(pi)
?>

输出：

By using 'M_SQRTPI' constant the value of PI : 1.7724538509055

示例5

<?php
echo "By using 'M_2_SQRTPI' constant the value of PI : ".M_2_SQRTPI; // 2/sqrt(pi)
?>

输出：

By using 'M_2_SQRTPI' constant the value of PI : 1.1283791670955