After trace(?asksign01); (internal function) I see that the
expression being tested is actually 1 - y^2.
Try assume(1 - y^2); I think that will answer the
question for the integral.
The assume stuff is, unfortunately, not very strong.
If you'd like to work on it, we would certainly appreciate the help.
best
Robert Dodier
On 3/4/11, alex <working.good at gmail.com> wrote:
> I cant really understand why assume doesnt work as it should to.
>
> Why maxima still asks the question, even though I did answer it with
> assume()??
>
> (%i23) assume( (y-1)*(y+1) > 0 )$ integrate(log(x^2+y^2),x,0,1);
> Is (y-1)*(y+1) positive, negative, or zero?
>
>
> But if I ask directly asksign() with this kind of assume it does work:
>
> (%i27) assume( (y-1)*(y+1) > 0 )$asksign( (y-1)*(y+1) );
> (%o27) pos
>
>
> I suspect it has smth with re-ordering of expression inside maxima
> before it outputs it, because:
>
> (%i4) -1+y;
> (%o4) y - 1
>
> I assume asksign() does this kind of reorder before outputting the
> question as well, while internally has different representation of the
> expression.
>
> My question is: can I turn off this reorder somehow so asksign() will
> write their questions properly, so I can use output of its question in
> assume() then.
>
> Thnx,
> Alex
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