[Matlab-emacs-discuss] executing matlab in org mode files (using the matlab-shell)

[Uwe B. <ou...@ma...>]

Hi

I am using more and more org mode, a long with auctex and matlab.el.
Orgmode comes in handy if I write a document which contains (matlab)
code which I want to execute, but the rest of the file maybe text, which
I can then export to latex.

So a typical file looks like

Given
\droppoints
\begin{displaymath}
      \begin{cases}
        \frac{du}{dt}&= -t u^2,\\
        u(0)&=1,
      \end{cases}
    \end{displaymath}

Solve using ...


#+BEGIN_solution
#+begin_src matlab :results output latex :exports results  :eval never-export 
f=@(t,y)[-t*y^2];
[t,y]=mieuler(f,[0 1],1,2);
disp('\begin{align*}')
fprintf('t = [%g \\qquad %g \\quad %g]  \\\\\n', t)
fprintf('y = [%g \\qquad %g \\qquad %g] \n', y)
disp('\end{align*}')
#+end_src

Now I can execute the matlab code in that org file using

C-c C-c ( org-ctrl-c-ctrl-c, the *one-ring-to-rule-them-all* function in
orgmode.

Thanks thanks to a function provided to me by John Kitchin it executes
matlab.

It is as follows:

(defun org-babel-execute:matlab (body params) 
  (interactive "P")
  (let* ((current-file (buffer-file-name)) 
	 (code (org-element-property :value (org-element-context)))
	 (result-params (cdr (assoc :result-params params)))
	 m-file
	 md5-hash)
    (with-temp-buffer 
      (insert code)
      (setq md5-hash (md5 (buffer-string))
	    mbuffer (format "*m-%s*" md5-hash)
	    m-file (format "m-%s.m" md5-hash)))
    ;; create the file to run
    (with-temp-file m-file 
      (insert code))
    (let ((results (shell-command-to-string
		    (concat
		     "/usr/local/bin/matlab "
		     "-nodesktop -nojvm -nosplash -nodisplay <"
		     m-file))))
      (delete-file m-file)
      (when results
	;; strip out >>
	(setq results (replace-regexp-in-string ">> " "" results))
	;; remove first 10 lines that are the header.
        ;; matlab license seem to expire soon, so 5 warning lines are added
        ;; change first 10 to first 15 lines
	(setq results (mapconcat 'identity
				 (nthcdr 10 (split-string results "\n"))
				 "\n")))
      (org-babel-result-cond result-params
	results))))

The problem of that  code is that it starts matlab every time I execute
C-c C-c . There seems to be a python based kernel around which avoids
this, but I thought that maybe with a bit of hacking one could use the
elisp based matlab-shell and the corresponding functions.

Anybody has an idea, Eric?
Needless to say that I played a bit around but did get it to work....

Regards

Uwe Brauer