[babel] how to pass data to gnuplot from another block

[Eric S Fraga <e.fraga@ucl.ac.uk>]

Hello,

everything I have seen on the list and on Worg seems to indicate that it
should be possible to pass data from a babel src block to a gnuplot src
block.  See, for instance, the excellent article on data collection and
analysis at

http://orgmode.org/worg/org-contrib/babel/examples/data-collection-analysis.html

I don't have R so I have not tried the examples on this page.  However,
I have tried the following using octave and gnuplot:

#+begin_src org
  ,#+TITLE:     examplebug.org
  ,#+AUTHOR:    Eric S Fraga
  ,* bubble and dew points
  ,#+name: bubble-point-temperatures
  ,#+begin_src octave :results raw output
    A = [   6.86880    6.84941]';
    B = [1154.646   1206.001]';
    C = [ 226.046    223.148]';
    pv = @(T) 10.^(A-B./(T+C));
    x = 0;
    res = [];
    while x<(1+1e-3)
      f = @(T) 760 - [x (1-x)]*pv(T);
      T = fsolve(f, 70);
      printf("| %5.2f | %7.2f | \n", x, T);
      res = [res; [x T] ];
      x = x + 0.05;
    endwhile
  ,#+end_src
  
  ,#+begin_src gnuplot :var data=bubble-point-temperatures :file "bubble.pdf"
    set terminal pdfcairo mono enhanced font ",12" size 10cm,6cm
    plot data
  ,#+end_src
  
  ,#+results:
  [[file:bubble.pdf]]
#+end_src
  
Trying to execute the gnuplot block leads to an error in gnuplot because
the output of the octave data block is being put directly into the data
variable instead of into a file whose name is passed to the data
variable.  The latter happens if the source of the data is a table
instead of a src block.

I have tried various combinations of output directives for the first src
block but to no avail.

I have tried this with "emacs -Q", by the way, and my org is up to date
as of a few minutes ago!

What am I doing wrong please?

Thanks,
eric

-- 
: Eric S Fraga (0xFFFCF67D), Emacs 24.3.50.1, Org release_8.2.3c-266-g7a726d