From help-octave-request at bevo dot che dot wisc dot edu  Thu Feb  1 10:44:44 2001
Subject: Re: plotting in 3D
From: Ben Sapp <bsapp at lanl dot gov>
To: courtois at ensia dot inra dot fr, help-octave@bevo.che.wisc.edu
Date: Thu, 01 Feb 2001 09:44:43 -0700

courtois at ensia dot inra dot fr wrote:
> 
> On  1 Feb, Etienne Grossmann wrote:
> >
> >   Hello,
> >
> > From: courtois at ensia dot inra dot fr
> > #  Hi
> > #
> > #  I don't understand how to plot in 3d a matrix (30 x 3). I read
> > #  sombrero.m but in my case the mesh is partial, and the "gset
> > #  parametrics" is ununderstandable.
> > #
> > #  any help ?
> >
> >   What about :
> >
> > octave:361> [x, y] = meshgrid (linspace (-10,10,30),linspace (-10,10,30));
> > octave:362> z = sin (x) + y.^2/100;
> > octave:363> mesh (x, y, z)
> 
> the problem is that I have already x y z in a matrix. So I don't have a
> complete mesh. I have difficulties to explain myself in english. In fact
> x y z (in matrix A) is partial experimental design with results in
> column z

Do I understand correctly that you actually want a 3-d trajectory and
not a mesh?  A mesh is only good for a surface.  If that is the case
then I think I have solved this exact problem a few months back.  The
function I wrote does no type checking what so ever.  I wrote it because
I needed to plot the trajectory of a differential equation.  
You may need to transpose your matrix if the dimensions don't agree with
what the function expects.  It expects x to be in the first column, y in
the second column, z in the third column.  

The Function:
------------------------------------------------------
function plot3d(x)
  name = tmpnam();
  [id,msg] = fopen(name,"w");
  for i = 1:(size(x)(1))
    fprintf(id, "%f %f %f\n",x(i,1),x(i,2),x(i,3));
  endfor
  fflush(name);
  cmd = sprintf("gsplot \"%s\"\n",name);
  eval(cmd);
  fclose(name);
endfunction
--------------------------------------------------------

Good luck.  

-- 
Ben Sapp                         Los Alamos National Laboratory
email: <mailto:bsapp at lanl dot gov>   Phone: (505)667-3277
Fax:   (505)665-7920             URL:   http://www.neutrino.lanl.gov/
--



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