first off your equation is ambiguous:
a) INT(0,pi) e(x2)
or
b) INT(0,pi) (ex)2
next, which do you want:
1) You just want the answer. Why are you asking on this forum?
you might want to ask dr math:
http://mathforum.org/library/drmath/view/53644.html
2) You want an algorithm to solve this particular problem, because you have to calculate it using php for some reason. Fair enough. though you should be able to find the solution somewhere else and then use php to do this easy easy without having to use the message boards.
use these resources once you have a solution you can work with:
http://www.php.net/manual/en/language.operators.arithmetic.php
http://www.php.net/manual/en/control-structures.php
3) You want to know how PHP would make a general case Integration Engine. tough one. beyond me. probably should not be done with somehting as slow as php.
