Re: [help] FFT & Spectrogram

[Jaroslav Hajek]

On Thu, Jul 2, 2009 at 8:53 AM, Judd Storrs<address@hidden> wrote:
> On Thu, Jul 2, 2009 at 2:01 AM, febty febriani <address@hidden> 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