On Wednesday 11 February 2009 15:48:37 Lorenzo Isella wrote:
> (%i5) integrate(abs(sin(x)), x, 0 , %pi);
> %pi
> /
> [
> (%o5) I abs(sin(x)) dx
> ]
> /
> 0
>
> So, it looks like that maxima (as expected!) has no trouble in
> calculating definite integrals of simple trigonometric functions,
> but if I add an absolute value, even if it has no effect on the
> sinus in the selected interval, then it returns what (according to
> some reading I did) stands for its inability of calculating the
> integral analytically.
> Why is that? Am I misunderstanding anything?
integrate does not handle abs. abs(sin(x)) could be simplified to
sin(x) in this case, but Maxima can't do it:
(%i1) assume(x >= 0 and x <= %pi);
(%o1) [x >= 0,x <= %pi]
(%i2) sign(x);
(%o2) pz
(%i3) abs(x);
(%o3) x
(%i4) sign(sin(x));
(%o4) pnz
(%i5) abs(sin(x));
(%o5) abs(sin(x))
--
Boomtime, Chaos 42 YOLD 3175
Alexey Beshenov http://beshenov.ru/