problems getting plots with octave/gnuplot

[Lissy Hennig]

problems getting plots with octave/gnuplot.

Hi.

I can plot e.g. 
x = (0:100)
plot(x,sin(x)) 

and get the right looking plot.

If I use the example from
help specgram :


   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);

I get an empty plot window, where the axis and labals are displayed only.

I use:
Mac OS X Intel
Octave 3.0.3 from SourceForge: in /Applications
  - signal package: $HOME/octave/signal-1.0.8
Gnuplot 4.0.0 from Fink: in /sw/bin/gnuplot
export GNUTERM="aqua"  is set in .profiles


Any suggestions how to solve the problem?

Thanks so much!

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