Named Constants
PHP provides the following named constants. Not all constants are available in all versions of PHP, and only M_PI is available in any version of PHP 3.
| Named Constant | Value | Description | Availability |
|---|---|---|---|
| M_1_PI | 0.31830988618379067154 | 1 / pi | PHP 4 RC 1+ |
| M_2_PI | 0.63661977236758134308 | 2 / pi | PHP 4 RC 1+ |
| M_2_SQRTPI | 1.12837916709551257390 | 2 / sqrt(pi) | PHP 4 RC 1+ |
| M_E | 2.7182818284590452354 | e; natural logarithm base | PHP 4 RC 1+ |
| M_EULER | 0.57721566490153286061 | Euler’s constant | PHP 4.0.2+ |
| M_LN2 | 0.69314718055994530942 | loge2 | PHP 4 RC 1+ |
| M_LN10 | 2.30258509299404568402 | loge10 | PHP 4 RC 1+ |
| M_LNPI | 1.14472988584940017414 | logepi | PHP 4.0.2+ |
| M_LOG2E | 1.4426950408889634074 | log2e | PHP 4 RC 1+ |
| M_LOG10E | 0.43429448190325182765 | log10e | PHP 4 RC 1+ |
| M_PI | 3.14159265358979323846 ... |
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