Re: [Maxima-discuss] bug in tex for a matrix

[Leo B. <Leo...@um...>]

On Wed, Apr 23 2025, Robert Dodier <rob...@gm...> wrote:

> On Wed, Apr 23, 2025 at 12:38 PM Leo Butler <Leo...@um...> wrote:
>>
>> This is a limit in tex:
>>
>> https://stackoverflow.com/questions/2789416/typesetting-a-large-matrix-in-latex
>>
>> The solution, made clear in the second answer, is to do something like
>>
>> \setcounter{MaxMatrixCols}{30}
>>
>> See also: https://sourceforge.net/p/maxima/bugs/4332/#7f8b
>
> There is a different implementation of TeX output for a matrix in
> share/utils/mactex-utilities.lisp, which makes use of \begin{pmatrix}
> and \end{pmatrix}. I think load("mactex-utilities.lisp") should find
> it. Does that obviate the problem with the maximum number of columns?

No, it does not, as you can confirm by loading that package into an
imaxima session and creating a matrix with ≥ 10 columns (the SO question
I cite found the problem using the amsmath `bmatrix' environment.)

The following does work (again, tested using imaxima):

texput(matrix,lambda([expr], printf(false,"\\setcounter{MaxMatrixCols}{~a}\\begin{pmatrix}~%~{~{~a~^&~}~^\\\\~}~%\\end{pmatrix}",length(first(args(expr))),map(lambda([row],map(tex1,row)),args(expr))))) $


>
> I gather that \begin{pmatrix} / \end{pmatrix} is from AMSTeX. Is that
> a reason to avoid it?

I guess this is a perennial question about the `tex' command; the
command's name suggests that it should emit valid TeX (\pmatrix //
\endpmatrix), not LaTeX (\begin{pmatrix} // \end{pmatrix}).

The current version of mactex.lisp does use \pmatrix if it is available.

> Should we consider moving TEX-MATRIX from
> share/utils/mactex-utilities.lisp to src/mactex.lisp?

I don't think so. Although it is easier to read the output, it violates
the presumption that `tex' generates valid TeX.

The same SO link suggests using the `+bmatrix' environment from the
tabularray package. Apparently, this obviates the need to set
`MaxMatrixCols'.

Leo