From maintainers-request at octave dot org Tue Mar 22 21:16:32 2005
Subject: Re: quiver question
From: Paul Kienzle <pkienzle at users dot sourceforge dot net>
To: octave maintainers mailing list <maintainers at octave dot org>
Date: Tue, 22 Mar 2005 22:24:05 -0500


On Mar 22, 2005, at 10:01 PM, John W. Eaton wrote:

> On 22-Mar-2005, Paul Kienzle <pkienzle at users dot sourceforge dot net> wrote:
>
> | The quiver problem on the current Debian octave-forge
> | confuses me.
> |
> | The following does not work:
> |
> | 	gplot M w v t ""
> |
> | The following works:
> |
> | 	gplot '/tmp/oct-XXXXX' w v t ""
> |
> | where /tmp/oct-XXXXX contains the contents of the 4-column M.
>
> I tried saving some 4-column data to a file and using
>
>   plot 'foo.dat' w v t ""
>
> and gnuplot complained:
>
>   gnuplot> plot 'foo.dat' w v t ""
> 			      ^
> 	   expecting 'lines', 'points', 'linespoints', 'dots', 'impulses',
> 	  'yerrorbars', 'xerrorbars', 'xyerrorbars', 'steps', 'fsteps',
> 	  'histeps', 'filledcurves', 'boxes', 'boxerrorbars', 
> 'boxxyerrorbars',
> 	  'vectors', 'financebars', 'candlesticks', 'errorlines', 
> 'xerrorlines',
> 	  'yerrorlines', 'xyerrorlines', 'pm3d'
>
> so what is a valid gnuplot plotting command that works so I can
> understand what you are trying to plot.

I'm trying to make a vector plot.  Here's more detail:

   [x,y] = meshgrid(1:2:20);
   u = sin(2*pi*x/10);
   v = sin(2*pi*y/10);
   M = [x(:), y(:), u(:), v(:)];

   system("rm /tmp/oct-*")
   gplot M w v t ""

This gives the error message:
          line 0: Not enough columns for this style

The following works (of course with Be4VTj replaced with whatever
was generated for your system):

   ls /tmp/oct-*
   gplot '/tmp/oct-Be4VTj' w v t ""


You may want to try 'w vec' or 'with vectors' or something like
that.

octave:26> OCTAVE_VERSION
OCTAVE_VERSION = 2.1.66

         G N U P L O T
         Version 4.0 patchlevel 0
         last modified Thu Apr 15 14:44:22 CEST 2004
         System: Linux 2.4.20-xfs


- Paul