[PD] is this a spectral gate?

Frank Barknecht fbar at footils.org
Thu Feb 22 08:33:36 CET 2007

Josh Steiner hat gesagt: // Josh Steiner wrote:

> what is the advantage of spitting out these values in polar coords?

According to the DSP-Guide it this:

  When should you use rectangular notation and when should you use
  polar? Rectangular notation is usually the best choice for
  calculations, such as in equations and computer programs. In
  comparison, graphs are almost always in polar form. As shown by the
  previous example, it is nearly impossible for humans to understand the
  characteristics of a frequency domain signal by looking at the real
  and imaginary parts. In a typical program, the frequency domain
  signals are kept in rectangular notation until an observer needs to
  look at them, at which time a rectangular-to-polar conversion is done.


Probably Miller thinks of Pd primarily as a tool for calculations so
he kept the re/im representation. I also think, that the algorithm to
calculate the Fourier transform, the Fast-FT or FFT, generates re/im
pairs, so skipping the final conversion to polar unless necessary
is faster. But I need to verify this. Maybe some DSP expert (Chuck?)
can confirm this?

 Frank Barknecht                 _ ______footils.org_ __goto10.org__

More information about the Pd-list mailing list