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.
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。
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.