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imagesc (specgram) problem


From: Schirmacher, Rolf
Subject: imagesc (specgram) problem
Date: Fri, 10 Aug 2007 22:42:16 +0200

Hello,

imagesc does not work as expected for me.

When I try the test / demo from the man page of specgram, I get

octave.exe>    x = chirp([0:0.001:2],0,2,500);  # freq. sweep from 0-500
over 2 sec.
   Fs=1000;                  # sampled every 0.001 sec so rate is 1 kHz
   step=ceil(20*Fs/1000);    # one spectral slice every 20 ms
   window=ceil(100*Fs/1000); # 100 ms data window
   specgram(x, 2^nextpow2(window), Fs, window, window-step);
octave.exe> octave.exe> octave.exe> octave.exe> 
gnuplot> set palette file "-" binary record=64 using 1:2:3:4;
                                                            ^
         line 0: Gray scale not sorted in gradient.

and a nearly completely black result with some coloured spots in the total
left column of the figure (it is a coloured result, as can be seen from the
colorbar, but there is no labelling at the bar).
After issuing toggle_octplot and trying again, octplot shows a reasonable
grayscale picture, no colorbar and an imediate error window indicating that
the program caused a problem and is going to close. The number in that error
message is 35846 and I am asked whether I would like to have a dump file.

I am using 2.9.13 under Win XP and the precompiled package.

Any idea?

Thanks in advance,

Rolf 


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