Re: Maxwell's density function grinds Octave

[Paul Thomas]

Henry F. Mollet wrote:

> Why is a problem of running out of colors rather than only a problem of too
> fine a grid?  I only get two colors, red outside and green inside of what
> can be seen of the saddle.
Yes, that is what I saw too.  However, the last message from gnuplot, 
before it fell off this mortal coil, was that it was running out of 
colours.  Mine is a pre-release version 4.0.

However, a 2001x731 mesh does seem to be unnecessily fine - wire 
surfaces tend to look better when open because of the reduced tendency 
of concentrations of lines on the image plane do go black.

Paul T

> GNU Octave, version 2.1.46 (powerpc-apple-darwin6.6)
> G N U P L O T Version 3.8i patchlevel 0
> Henry
>
>
> on 8/21/04 4:40 AM, Paul Thomas at address@hidden wrote:
>
>  
>
> > Reduce the mesh dimensions by a factor 20x10!
> >
> > ie.
> >
> >    
> >
> > > V = 0:20:2000;
> > > t = 273.15:10:1073.15;
> > >      
> > octave did OK with the original but Gnuplot crashed!  Matlab R13 does not do
> > well with the original mesh either.  Both run out of colours for the plot.
> >
> > Paul T
> >
> > ----- Original Message -----
> > From: "Gad Abraham" <address@hidden>
> > To: <address@hidden>
> > Sent: Saturday, August 21, 2004 10:18 AM
> > Subject: Maxwell's density function grinds Octave
> >
> >
> >    
> >
> > > Hi,
> > >
> > > I've been trying to plot Maxwell's speed distribution equation for ideal
> > > gases on Octave, using the following code (adapted from a matlab script
> > > on http://chemistryresources.tripod.com/physical/maxwell.txt):
> > >
> > > function surf(varargin) mesh(varargin{:}); endfunction
> > >
> > > M = 32e-3;
> > > R = 8.31451;
> > >
> > > V = 0:1:2000;
> > > t = 273.15:1:1073.15;
> > >
> > > [v, T] = meshgrid(V, t);
> > >
> > > f = 4*pi*((M./(2*pi*R.*T)).^(3/2)).*(v.^2).*exp(-M.*(v.^2)./(2*R*T));
> > >
> > > surf(v,T,f);
> > >
> > > xlabel('v');
> > > ylabel('T');
> > > zlabel('f');
> > >
> > >
> > > The problem is that on my rather fast machine (AthlonXP2800, 768MB RAM),
> > > this grinds away for almost 10 minutes, and the end result is a gnuplot
> > > window with a only few tiny lines in it.
> > >
> > > I'm using Octave2.1, gnuplot 4.0, on Debian Linux.
> > >
> > >
> > > Any advice?
> > >
> > >
> > > Thanks,
> > > Gad
> > >
> > > --
> > > http://chookies.homeunix.org
> > >
> > >
> > >
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> >    
>
>
>  




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