----- Original Message ----- From: "Greg Berchin" <[EMAIL PROTECTED]> > >If you want to see this for yourself, take a GP implementation of a > >lowpass filter and turn down the turnover frequency to a few Hz, unless > >the programmer has been clever and sacrificed some quailty and speed > >the cpu use will go up by 40% or so. A jump in CPU usage may indicate that the FPU is getting numeric underflows which can interrupt the CPU! This can easily happen in IIR filters where the internal values decay exponentially closer and closer to zero. This can be avoided by adding very small values, like alternating 1.0E-26 and -1.0E-26, to the filter's internal values. Phil Burk JSyn,pForth,DSP,ASIC - http://www.softsynth.com Portable Audio I/O - http://www.portaudio.com Interaction Server - http://www.transjam.com
