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Re: Newbie question
From: |
Joe Koski |
Subject: |
Re: Newbie question |
Date: |
Thu, 04 Aug 2005 17:19:05 -0600 |
User-agent: |
Microsoft-Entourage/11.1.0.040913 |
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
How to fund new projects: http://www.octave.org/funding.html
Subscription information: http://www.octave.org/archive.html
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