Re: [Maxima-discuss] varieties of invert, was: ratsimp not working as expected

[andre m. <and...@gm...>]

On 03/07/2014 08:16 PM, Robert Dodier wrote:
> On 2014-03-07, andre maute <and...@gm...> wrote:
>
>> --- ratsimp-bug3.max ---------------
>> display2d : false;
>> d : 4;
>> A : genmatrix(lambda([k,l],v[[k,l]]-v[[0,l]]),d,d);
>> Ainv : invert(A);
>> --- ratsimp-bug3.max ---------------
> Pretty sure you can avoid this bug by using a different implementation
> of 'invert'. Try load(invert); and then the code above -- works for me.
> That loads an implementation of the adjoint method -- the built-in
> default is based on LU factorization if I remember correctly.
>
> The problem is that there are various ways to compute the inverse and
> they work better or worse in different cases. Recently (maybe a year
> ago) yours truly changed the default implementation (after discussion
> on the mailing list). We've bumped into various problems with that so
> I've been meaning to rework it again. Sorry for the bother.
>
> I don't know whether this particular problem is at the heart of the
> ratsimp trouble you originally encountered.
Yes. I remember the discussion.
And yes Maxima 5.32.1 with GCL and load("invert") doesn't segfault anymore.

Regards Andre