http://www.wolframalpha.com/
Evo ti par primera
Code:
http://www.wolframalpha.com/input/?i=Int[r^2+Sin[theta]%2C+{r%2C+0%2C+R}%2C+{phi%2C+0%2C+2+pi}%2C+{theta%2C+0%2C+pi}]
http://www.wolframalpha.com/input/?i=Int[r+e^%28-a+r^2%29%2C+{r%2C+0%2C+inf}%2C+{phi%2C+0%2C+2+pi}]
#define TRUE FALSE /*Happy debugging suckers*/