Sun Jan 27 19:47:41 CET 2013
Loops in DSP: `feedback' is contextual
* To make things more explicit it should be understood that the
`feedback' form refers to some kind of "context". It is nothing
more than a preprocessing trick to create fold-style loops where
state feedback dominates.
* Stream processors are an "infinite loop", so the above isn't
immediately visible (no end, but there is an init that for now has
been glossed over. But it makes a lot of sense to have the same
kind of state feedback mechanism on a local level, i.e. for block
processing or iterative numerical algorithms.
* The big idea is that the siso system is the unifying structure for
numerical algorithms that operate on streams of data -- i.e. not the
'fold', not the 'map'.
- Syntactical need: Some DSP algorithms can get heavy on local loop
state. Removing the need to explicitly name this state helps a lot
to focus on inter-module dataflow.
- Representation need: Functional representation is good for analysis
(as opposed to destructive state updates)