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# LXIII. Mathematical Functions

# 介紹

These math functions will only handle values within the range of the integer and float types on your computer (this corresponds currently to the C types long resp. double). If you need to handle bigger numbers, take a look at the arbitrary precision math functions.

See also the manual page on arithmetic operators.

# 需求

建立這個延伸不需要任何外部程式庫。

# 安裝

這些函數是PHP核心的一部分，不需要安裝就可使用。

# 執行時期組態

`php.ini`中沒有定義此延伸的組態指令。

# 資源類型

這個延伸沒有定義任何資源。

# 預先定義常數

以下經常有效常數為PHP核心的一部分。

表格 1. Math constants

Constant | Value | Description
--- | --- | ---
M_PI | 3.14159265358979323846 | Pi
M_E | 2.7182818284590452354 | e
M_LOG2E | 1.4426950408889634074 | log_2 e
M_LOG10E | 0.43429448190325182765 | log_10 e
M_LN2 | 0.69314718055994530942 | log_e 2
M_LN10 | 2.30258509299404568402 | log_e 10
M_PI_2 | 1.57079632679489661923 | pi/2
M_PI_4 | 0.78539816339744830962 | pi/4
M_1_PI | 0.31830988618379067154 | 1/pi
M_2_PI | 0.63661977236758134308 | 2/pi
M_SQRTPI | 1.77245385090551602729 | sqrt(pi) [4.0.2]
M_2_SQRTPI | 1.12837916709551257390 | 2/sqrt(pi)
M_SQRT2 | 1.41421356237309504880 | sqrt(2)
M_SQRT3 | 1.73205080756887729352 | sqrt(3) [4.0.2]
M_SQRT1_2 | 0.70710678118654752440 | 1/sqrt(2)
M_LNPI | 1.14472988584940017414 | log_e(pi) [4.0.2]
M_EULER | 0.57721566490153286061 | Euler constant [4.0.2]

Only M_PI is available in PHP versions up to and including PHP 4.0.0. All other constants are available starting with PHP 4.0.0. Constants labeled [4.0.2] were added in PHP 4.0.2.

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