Uwe,

In my testing (using octave since I don't have matlab, but I hope it's
similar), using = :exports none :results output raw= seems to produce the
desired output:

#+begin_src octave :exports results :results output raw
close all
N = 3; % number of chebyshev nodes
n = 1; % polytropic index
iters = 1; % iterations
j=[0 1 2 3];
z=cos((pi*j)/3);
y=1-(0.5*(z+1)).^2;
a=n*(8);
a2=eye(3+1)*a;
disp('\begin{align*}')
disp('A_{1,k-1}&=')
disp('\begin{pmatrix}')
fprintf('%g &%g &%g &%g\\\\\n',a2')
disp('\end{pmatrix}=OK\\')
disp('\end{align*}')
#+end_src

#+RESULTS:
\begin{align*}
A_{1,k-1}&=
\begin{pmatrix}
8 &0 &0 &0\\
0 &8 &0 &0\\
0 &0 &8 &0\\
0 &0 &0 &8\\
\end{pmatrix}=OK\\
\end{align*}

Which renders the matrix correctly. I first tried with =:exports results=,
but that for some reason results in the results being included twice in the
LaTeX output. I'm not sure why.

Hope this helps,
--Diego


On Tue, Oct 13, 2020 at 1:36 PM Uwe Brauer <oub@mat.ucm.es> wrote:

> >>> "AB" == Arne Babenhauserheide <arne_bab@web.de> writes:
>
> > Uwe Brauer <oub@mat.ucm.es> writes:
>
> >> That did not work: I tried
> >> #+begin_src matlab  :results output
> >>
> >> But when I exported the org file to latex, the matlab code was also
> >> exported. Strange
>
> > Do you use :exports results?
>
> > :results output switches to show what is printed to stdout
>
> See my answer to Eric
>
> It does not do want I want
> #+begin_src matlab :exports results
> close all
> N = 3; % number of chebyshev nodes
> n = 1; % polytropic index
> iters = 1; % iterations
> j=[0 1 2 3];
> z=cos((pi*j)/3);
> y=1-(0.5*(z+1)).^2;
> a=n*(8);
> a2=eye(3+1)*a;
> disp('\begin{align*}')
> disp('A_{1,k-1}&=')
> disp('\begin{pmatrix}')
> fprintf('%g &%g &%g &%g\\\\\n',a2')
> disp('\end{pmatrix}=OK\\')
> disp('\end{align*}')
> #+end_src
>
> Leads to
>
> \begin{verbatim}
> \begin{align*}
> A_{1,k-1}&=
> \begin{pmatrix}
> 8 &0 &0 &0\\
> 0 &8 &0 &0\\
> 0 &0 &8 &0\\
> 0 &0 &0 &8\\
> \end{pmatrix}=OK\\
> \end{align*}
> \end{verbatim}
>
> So at the moment the only solution I can think of is to use the code I
> posted
>
> (defun my-latex-filter-src-blocks (text backend info)
>   "Remove source blocks from latex export."
>   (when (org-export-derived-backend-p backend 'latex)
>     "%% [removed source block]\n"))
>
> (add-to-list 'org-export-filter-src-block-functions
>          'my-latex-filter-src-blocks)
>