[PD] Colored (fractal, 1/f^a) noise generator for PD

alberto.zin at poste.it alberto.zin at poste.it
Mon Aug 21 00:20:32 CEST 2006


Hi Mathieu

if I'm not wrong, as long as it is white it is flat
in spectral terms but the distribution
of amplitudes (probability density function, pdf) of white
noise can be gaussian, cauchy, uniform, etc. Therefore I'm
not sure that the spectrum is proportional to the pdf.. 

Alberto


On Sun, 20 Aug 2006, alberto.zin at poste.it wrote:

> You are right. BTW, I already wrote an external for
gaussian noise 
> generation (it is an easy adaptation of the noise code +
Box-Muller 
> transform to make it gaussian - not distributed yet
because I've to 
> clean up the code, it is my first external ;-). But it did
not change it 
> very much :-( In addition it seems that using noise~ is
still ok to have 
> the desired slope in the spectrum...

Doesn't a Gaussian distribution have a spectrum proportional
to its own 
density? That is, exp(-s^2/var)/sqrt(2*pi*var). That means
that in the dB 
vs octave graph, it would appear as a quadratic instead of a
straight 
line, and this doesn't match any of the examples shown in the 
Colors_of_noise article. Right?

  _ _ __ ___ _____ ________ _____________
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| Mathieu Bouchard - tél:+1.514.383.3801 -
http://artengine.ca/matju
| Freelance Digital Arts Engineer, Montréal QC Canada





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