I have been making some interesting compositions using the 
octdown and the Spectrum global operators of CSound, but I would like to
know which is the theory behing this operator. How can it reduce so much
the data and get so good results? Could anybody help me, please?

[]'s 

Hugo Bastos de Paula
hugo@dcc.ufmg.br
http://www.dcc.ufmg.br/~hugo