Pi is often usefull in con/sin/tan functions..

There are also other Pi related constants.

These are most of them:



M_PI = 3.14159265358979323846 // pi



// The following were added in PHP 4.0.0

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) (Only in PHP 4.0.2+)

M_2_SQRTPI = 1.12837916709551257390 // 2/sqrt(pi)