Re: [Help-gsl] Data Visualization

[James Bergstra]

Thank you for your suggestions for how to use Gnuplot, they have been exactly
what I was hoping to learn!

<$0.02>

Now about the 3D geometry...

Your point that blas routines are sub-optimal for small matrices is well-taken.
Something you might consider is making functions with the same signatures as
gsl_blas_xxx functions.  You could consider making  inline-able implementations
for them that check the input size, and behave accordingly.  For small matrices,
the calculations could be done inline; for large matrices, the work could be
passed on to ATLAS.

</$0.02>

James

On Wed, Dec 14, 2005 at 07:11:37PM +0100, Peter Melchior wrote:
> On Tue, 2005-12-13 at 20:06 -0500, Martin Jansche wrote:
> 
> > > - could plot matrices of data as images (taking each cell as a pixel?)
> > 
> > Kind of. It can be done, though gnuplot isn't specifically designed to
> > do that. Nothing that a little wrapper script couldn't cure. The basic
> > idea is to view the matrix as a collection of 3d points and to use
> > gnuplot's 3d plotting routines.  First, make a "pseudo 3d bar graph"
> > as described here:
> > 
> >   http://t16web.lanl.gov/Kawano/gnuplot/plotpm3d-e.html#6.9
> > 
> > Then color the surface (this requires gnuplot 4.0), switch off the
> > surface grid, and rotate the view so that you're looking at the
> > surface straight from above. That's the gist of it; I can dig up some
> > code if that would help.
> 
> It's quite easy: type "set pm3d map" in gnuplot
> (http://gnuplot.sourceforge.net/docs_4.1/node197.html).
> That does what Martin described. One little annoyance is that gnuplot
> needs a blank line between data blocks, when the first coordinate
> changes, like this:
> 
> x0 y0 2.41
> x0 y1 3.14
> x0 y2 3.67
> 
> x1 y0 3.33
> x1 y1 ...
> 
> But there's a awk script that deals with this problem:
> http://www.gnuplot.info/faq/faq.html#SECTION000510000000000000000
> 
> So what you then need to do is 
> 
> splot "< awk -f addblanks.awk Datafile"
> 
> where the matrix data is stored in Datafile as above but without the
> need for blank lines.
> 
> 
> Hope that helps,
> 
> Peter Melchior
> 
> 
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-- 
james bergstra
http://www-etud.iro.umontreal.ca/~bergstrj