[Maxima] maxima bug

[Robert Dodier]

On 3/9/12, Raymond Toy <toy.raymond at gmail.com> wrote:

>> reset();kill(all);
>> assume(z>r);
>> radcan(sqrt(r^2-2*z*r+z^2));
>>
>> it gives
>>
>> z-r
>>
>> works fine
>>
>> but with capital R
>>
>> reset();kill(all);
>> assume(z>R);
>> radcan(sqrt(R^2-2*z*R+z^2));
>>
>> it gives
>>
>> R-z
>>
>> should be
>> z-R

> I don't think this is a bug.  Radcan does sometimes do things like this and
> that is the expected result.  I don't think radcan recognizes assume either.

radcan ignores assume -- I think that's a bug. That the result depends on
the ordering of the variables is OK only if all possible results are
equally valid.
That's not the case when there are facts (stated by assume) to take into
account.

It's true that many functions in Maxima ignore assume. I don't think
that's desirable, although I do understand that it's hard to fix.

best

Robert Dodier