| 常量名 | 常量名 | 常量值 | PHP |
|---|---|---|---|
| M_E | e | 2.7182818284590452354 | 4 |
| M_EULER | Euler 常量 | 0.57721566490153286061 | 5.2.0 |
| M_LNPI | log_e(pi) | 1.14472988584940017414 | 5.2.0 |
| M_LN2 | log_e 2 | 0.69314718055994530942 | 4 |
| M_LN10 | log_e 10 | 2.30258509299404568402 | 4 |
| M_LOG2E | log_2 e | 1.4426950408889634074 | 4 |
| M_LOG10E | log_10 e | 0.43429448190325182765 | 4 |
| M_PI | Pi | 3.14159265358979323846 | 3 |
| M_PI_2 | pi/2 | 1.57079632679489661923 | 4 |
| M_PI_4 | pi/4 | 0.78539816339744830962 | 4 |
| M_1_PI | 1/pi | 0.31830988618379067154 | 4 |
| M_2_PI | 2/pi | 0.63661977236758134308 | 4 |
| M_SQRTPI | sqrt(pi) | 1.77245385090551602729 | 5.2.0 |
| M_2_SQRTPI | 2/sqrt(pi) | 1.12837916709551257390 | 4 |
| M_SQRT1_2 | 1/sqrt(2) | 0.70710678118654752440 | 4 |
| M_SQRT2 | sqrt(2) | 1.41421356237309504880 | 4 |
| M_SQRT3 | sqrt(3) | 1.73205080756887729352 | 5.2.0 |
注：PHP：指示支持该函数的最早的 PHP 版本。
原文：https://www.cnblogs.com/lxhyty/p/11466354.html