From mboxrd@z Thu Jan  1 00:00:00 1970
From: Neil Jerram <neil@ossau.homelinux.net>
Subject: Re: babel, matlab export plot to png fails
Date: Tue, 15 Aug 2017 11:12:40 +0200
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On 13/08/17 10:33, Uwe Brauer wrote:
> Hi
>
> I would like to execute some matlab code in org file (using GNU emacs 26
> and the git version of org mode) and save the result of the plot command
> in a png file, so I tried
>
> #+begin_src matlab :session :exports both :file testplot.png
> t=[0:0.1:1];
> y=sin(t);
> plot(t,y)
> print -dpng  testplot.png
> #+end_src
>
> And also
> #+begin_src matlab :results output latex :exports results  :file testplot.png
> t=[0:0.1:1];
> y=sin(t);
> plot(t,y)
> print -dpng  testplot.png
> #+end_src
>
> But the resulting png files are corrupt. I presume also the matlab
> commands are included in the png file which is not correct. But I don't
> know who to achieve that just the last command is saved in a png file.

I guess the problem is that the Matlab line "print -dpng testplot.png" 
is correctly writing the plot to testplot.png, as you want, but then 
org-mode is overwriting that file because of the ":file testplot.png".  
I would try deleting ":file testplot.png".

The meaning of ":results output" may be a bit language-dependent - I 
don't know org-mode well enough to be sure about that yet - but in 
general I would expect it to consist of the standard output of those 
commands.  So, for example, if you type "print -dpng testplot.png" and 
Matlab responds with "Generated 'testplot.png'", I would expect 
":results output" to contain "Generated 'testplot.png'", not the PNG data.

Regards - Neil