[help] FFT & Spectrogram

[febty febriani]

2009/7/2 Jaroslav Hajek <highegg at gmail.com>

> On Thu, Jul 2, 2009 at 8:53 AM, Judd Storrs<storrsjm at email.uc.edu> wrote:
> > On Thu, Jul 2, 2009 at 2:01 AM, febty febriani <febty82 at gmail.com>
> wrote:
> >>
> >> octave <<EOF
> >> Fs=1;
> >> fh=fopen("result.dat","r");
> >> x=fscanf(fh,"%lf");
> >> x0=hanning(4096);
> >> a=(x(1:4096)).*(x0);
> >> b=fft(a,8192);
> >> c=abs(b(1:4096));
> >> c=c/max(max(c))    ;
> >> d=((1:4096)/4096)*(Fs/2);
> >> subplot(2,1,1);plot(d,c);
> >> subplot(2,2,1);imagesc(flipud(20*log10(c)));
> >> EOF
> >
> > What I suspect is happening here is when octave reaches the EOF it exits
> and
> > doesn't draw the plots. Since there also aren't any commands to save the
> > plots to a file that is why you don't see any output. You can perhaps add
> a
> > "print" statement to get the plots to file
> > http://www.network-theory.co.uk/docs/octave3/octave_163.html
> >
> > Or if you would rather watch the plots you can add
> >
> > drawnow ;
> > sleep(10) ;
> >
> > before the EOF to pause 10 seconds before exiting. For the second subplot
> > you may want "subplot(2,1,2)" instead of "subplot(2,2,1)"
> >
> > Hope this helps,
> >
> > --judd
>
> As a side note, I think calling `drawnow' is redundant, because
> `sleep' does it intrinsically.
>
> --
> RNDr. Jaroslav Hajek
> computing expert & GNU Octave developer
> Aeronautical Research and Test Institute (VZLU)
> Prague, Czech Republic
> url: www.highegg.matfyz.cz
>

thanks alot. you are right. it was redundant. I eliminated it. but I had no
idea for error message "GNUPLOT (plot_image):  Image grid must be at least 2
x 2." for my script above.

any help is appreciated, please.


-- 

******
febty febriani
Indonesian Institute of Sciences
Research Center for Physics
Kompleks PUSPIPTEK
Serpong, Indonesia, 15314
-------------- next part --------------
An HTML attachment was scrubbed...
URL: https://www-old.cae.wisc.edu/pipermail/help-octave/attachments/20090702/b6d2dcd4/attachment.html