On Tue, Jul 8, 2008 at 12:52 AM, William Stein <[EMAIL PROTECTED]> wrote:
>
> On Mon, Jul 7, 2008 at 9:12 PM, Elliott Brossard
> <[EMAIL PROTECTED]> wrote:
>> Hi William,
>>
>> I am becoming more familiar with both Linux and Sage now, which makes things
>> much easier. I finished porting the Maxima and Wester integration tests to
>> Sage, though there are many that currently fail...I've attached them, if
>
> You attached only the ones that fail? Where are the ones that succeed?
>
Perhaps we can setup a new tests repo for the very large test suite
currently under development? Alternatively we could stick it in new
symbolics, but that would change term ordering. In any case I'd like
to try the test suite myself.
>> you'd like to see. The problem that many of them have results from ambiguity
>> of variables under a radical, in a denominator, or in a function with a
>> restricted domain. As an example, inputting
>
> Can you just make a new test that tests each case?
>
+1
>> var('a')
>> integrate(log(x)/a, x, a, a+1)
>>
>> will throw an error: 'is a positive or negative?' Two assume
>> statements--assume(x+a+1>0) and assume(a-1>0)--render Sage capable of
>> responding, and it outputs
>>
>> ((a + 1)*log(a + 1) - a*log(a) - 1)/a
>>
>> My TI-89 calculator, which uses Derive, gets the same result, though without
>> using 'assume' in any form. Trouble is, I can't imagine there's a quick fix
>> for this, and since most of the failing integrals are from Maxima's own test
>
> It would likely be possible -- though difficult (maybe not too difficult) --
> to have Sage automatically give all possible answers to Maxima and
> construct a conditional integral expression that gives each possible
> answer for given conditions.
>
I think this is a good idea if we want to go down the derive road, but
it is not clear to me that this is the best idea. The number of
different piecewise expressions here could blow up very quickly.
However, the alternative of 100% ignoring everything else seems like a
bad idea too, so the piecewise route is probably best.
>> suite, they must already know about it. Some of the other failing
>> integration tests are merely identities that the current version of Maxima
>> likely fixes...at least I hope so. I also wrote a series of tests for the
>> various rules of differentiation, though all of them check out fine.
>
> You can get the current version of Maxima presumably from the maxima
> website.
>
>> What I would like to start on next is the calc101 sort of website that I
>> discussed with you before, though I was wondering if we could meet to go
>> over the specifics of how I would implement it. I'll be at the UW on
>> Thursday for a class from 3-5pm, so I would be happy to meet with you
>> beforehand or afterward, though if that doesn't work another day would be
>> fine as well.
>
> I am in San Diego. I could meet with you next week maybe, but I'm
> not sure since I'm going to Europe on the morning of the 16th.
>
If nothing else we could meet and talk about Symbolics/Maxima if your
interested.
> -- William
>
> >
>
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