Sun Aug 14 15:36:40 CEST 2011


Back to the sawtooth example.  It's a nice one because it has:
  - different data types (int, float)
  - time dependency
  - nonlinearity

The mix of time-dependency and nonlinearity means that the only simple
representation (I can think of) is as a state-space model.

Actually, the int is not really an int, it's used as a phasor (angle).

 \ (th, x2, freq) -> (th', x2', out)  where

   th'  = th + freq   -- update phasor
   x    = ph2i th     -- convert phasor to [0,1[
   x2'  = x * x       -- square
   out  = x2 - x2'    -- filter (differentiate)

( very wrong, but the idea seems ok. )