Plotting problem

[Matthias Brennwald]

Dear all,

before reading further, a short warning: I'm a newbie (both with  
Octave and with this list), so...

I am trying to write some code that plots a "waterfall diagram" (aka.  
"cumulative spectral decay diagram", CSD diagram). An example of such  
plot is available here: http://www.euronet.nl/users/temagm/audio/ 
waterfall_focal.htm

I want this code to work both under Matlab and Octave. I use Octave  
2.1.72 on the Mac, but the code should not be limited to this  
specific setup.

My approach to plotting the waterfall is this (see also example code  
below): first, plot the curve in the back as a filled polygon. Then,  
plot the next curve also as filled polygon above the one in the back;  
and continue in the same way until the frontmost curve. With Matlab,  
I can use 'fill3' easily plot these polygons. With plain vanilla  
Octave, the only options I have is 'mesh' or '__gnuplot_splot__',  
which I cannot make plot FILLED polygons. (I also tried the 'fill3'  
command from Octave-forge, but with no luck. Also, I want my code to  
be independent of Octave-forge, because Octave-forge is not available  
as a 'stable' version from Fink for easy installation on the Mac.)

Any help or ideas?

Matthias




An example illustrating my approach (and problem) is this:

**********************
% First, make up three curves z(x) to play with. Each of the curves  
have constant y (y=1,2,3):
x = [0:100];
y = [ 0:2 ];
z = [   2+sin(x/10);
        1.8 + 0.8*sin(x/11);
        1.5 + 0.6*sin(x/12); ];

% append some points so we get closed curves:
x = [ x x(end) x(1) x(1) ];
z = [ z [0 0 0]' [0 0 0]' z(:,1) ];

for n=1:3
    if exist('OCTAVE_VERSION') % we're running Octave
        mesh(x,y(n),z(n,:)); % this plot TRANSPARENT polygons
    else % we're running Matlab
        poly=fill3(x,repmat(y(n),1,length(z(n,:))),z(n,:),'w'); %  
this plots a filled polygon with fill color 'white'
        set(poly,'EdgeColor','r'); % this sets the edge of the  
polygon to 'red'
    end
    hold on
end

hold off
**********************




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Matthias Brennwald
Lägernstrasse 6
CH 8037 Zürich
+41 (0)44 364 17 03
address@hidden