Re: Newbie question

[Joe Koski]

When a graphical output has a continuous range of color or gray scale, such
as a photograph, octave doesn't currently have a way to pass scale
information to gnuplot/aquaterm. As a workaround, Paul Kienzle's bmpwrite.m
is used for image.m on a Mac. This allows the image to be written into the
.bmp format, which is then automatically opened by the OS X in Preview.

The latest gnuplot 4.0/Aquaterm 1.0 combination now has color/gray scale
capabilities. It's a matter of developing the necessary routines.

Joe


on 8/4/05 4:57 PM, Henry F. Mollet at address@hidden wrote:

> I've recently pointed out a similar problem with respect to contourf(z) in
> octave-forge. The output is sent to Preview and I don't understand why.
> Henry
> octave:62> gset term aqua 0
> octave:63> [x,y] = meshgrid(linspace(-2,2,200));
> octave:64> z = sinc(sqrt(x.^2 + y.^2));
> octave:65> contourf(z);
> error: expecting integer index, found 7.300000
> error: evaluating argument list element number 1
> error: called from `contourf' in file
> `/usr/local/share/octave/2.1.71/site/m/octave-forge/plot/contourf.m'
> 
> octave:65> contourf(z); % works when used for the second time and output
> appears in Preview rather than Aquaterm.
> 
> ## contourf(z,n,w)
> ## Plots a filled contour plot of n levels using the current
> ## colormap.  The width w is the width of the convolution window
> ## which smooths the contours.
> ##
> ## E.g.,
> ##     [x,y] = meshgrid(linspace(-2,2,200));
> ##     z = sinc(sqrt(x.^2 + y.^2)) + 0.5*randn(size(x));
> ##     contourf(z);
> ##
> ## Note that the algorithm computes incorrect contours near the
> ## edges, which you can see using contourf(sinc(sqrt(x.^2+y.^2)))
> ## with x,y from above.
> 
> ## This program is in the public domain
> ## Author: Paul Kienzle <address@hidden>
> 
> function contourf(z,n,w)
>   if nargin < 3, w = 16; end
>   if nargin < 2, n = 10; end
>   if nargin < 1 || nargin > 3
>     usage("contourf(z [, n [, w]])");
>   endif
> 
>   ## convolute the original with a gaussian if desired
>   if w > 0
>     [x,y] = meshgrid(2.5*linspace(-1,1,w));
>     B = exp(-.5*(x.^2+y.^2));
>     z = filter2(B,z,"same");
>   endif
> 
>   ## find the contours
>   C = colormap;
>   colormap(repmat(linspace(0.5,1,n+1)',1,3));
>   z = filter2(ones(2)/4,imagesc(z));
>   z(z!=fix(z)) = 0;
> 
>   ## plot the image, with the contours drawn in black.
>   colormap([0,0,0; C(linspace(1,rows(C),n+1),:)]);
>   image(flipud(z)+1);
> 
>   ## restore the colormap
>   colormap(C);
> endfunction
> 
> 
> on 8/4/05 2:17 PM, Melvyn Poore at address@hidden wrote:
> 
>> Hi folks, I¹m new on the block, so forgive me for asking beginner¹s
>> questions.  I¹ve installed Octave 2.1.71, Gnuplot, Aqua and X11 on my Mac Ti
>> Powerbook 550MHz, OSX 10.4.2.  It all appears to function as it should.
>> That was already quite an achievement!
>> 
>> I¹m working on some sound analysis examples and want to put the waveform and
>> spectrogram plots together in a two-plot diagram.  This doesn¹t seem to work
>> because plot() sends its results out via Aqua whereas the output of
>> imagesc() appears in a Mac Preview window.  Am I missing some terminal
>> setting or something?  I¹ve already set the line
>> 
>> __gnuplot_set__ term aqua
>> 
>> in startup/octaverc.
>> 
>> Any help would be appreciated!
>> 
>> Melvyn
> 
> 
> 
> 
> 
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Octave is freely available under the terms of the GNU GPL.

Octave's home on the web:  http://www.octave.org
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