Micro-update

Today I was trying to finish recursive vector code, and of course lots of other things interfered. Several things happened today:

• Fixed radix expansion of DftCt with left recursion in Maude, will produce a tail-recursive program, which can be converted into a loop. This has nice parallel with what FLAME is doing.
• I talked to Franz and there are several issues with scalability of Spiral. We need to be able to compose several different codes: real, complex, FMA, fixed-point, vector, SMP, recursive and so forth.

Automatic iterative DFT construction is very nice, and easy to to in Maude. I will do this one day. Franz also showed me how to get a large sample of iterative variants automatically (Pease, Stockham, Korn-Lambiot, etc).

The scond main issue is scalability of Spiral. Here we came up with a list of TODOs:

1. RulesFor(pattern, ...) (for example [TRC, [DFT, @]])
2. Composable unparsers
1. C99Unparser, TRC, TCR, TCC
2. Composable CodeRuleTree, or at least one should resolve all conflicts within different modes
3. This is complete when TCR(RDFT(..)) produces assymmetric code (real input, complex output)
3. SPL/DP options record expansion. Franz also suggested the idea of "worksheet". Worksheet would keep options along with all intermediate results (ie. ruletree, formula, sigma-spl formula, and finally code). This should simplify conflict resolution
4. Eliminate all global variables (2 and 3 basically do this)
5. DP should return code + file where it is stored.