On Mon, Jul 11, 2011 at 10:30 AM, Pedro Cruz <[email protected]> wrote:
> Good morning,
>
> the command
>    integrate( abs(x^2-1), x, -2,2)
> does not do the job automatically.
>
> I have seen on this discussion group another, at least, similar
> message.
>
> Is there an organized list of functions that are yet implemented for
> integration?

Sage's symbolic integration is currently just calling out to Maxima,
so you might ask about this on a Maxima list.  Maxima's symbolic
integration is some huge undocumented lisp program from ages gone
by...

The above doesn't return a closed result partly because Maxima doesn't:

wstein@sage:~$ sage -maxima
Maxima 5.23.2 http://maxima.sourceforge.net
(%i1) integrate(abs(x^2-1),x,-2,2)
;
                                2
                               /
                               [    ! 2    !
(%o1)                          I    !x  - 1! dx
                               ]
                               /
                                - 2


You might find this useful though:

sage: numerical_integral(abs(x^2-1),-2,2)
(3.9999999999999996, 4.4408920985006262e-14)

or

sage: N(integral(abs(x^2-1),(x,-2,2)))
3.9999999999999996


> How can one cooperate without being a sage programmer?

>
> Thank you.
>
> Pedro
>
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-- 
William Stein
Professor of Mathematics
University of Washington
http://wstein.org

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