[macstl-dev] Interleave/transpose function -- opinions wanted

[Glen Low]

Hi All

Andrew Brownsword would like interleave/transpose functions added to  
macstl valarrays and it is a sensible and interesting addition, so  
I'm going to be pursuing it for 0.3.x.

Given a valarray v = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9 ...}

Then deinterleave <n, m> (v) = {n, n+m, n+2m ... } e.g. deinterleave  
<0, 4> (v) = {0, 4, 8 ... }

and

interleave (x, y, z ... ) = { x0, y0, z0 ... x1, y1, z1 ... } etc.

Obviously for the right values of n, m and # of parameters in  
interleave (and types), suitable Altivec or SSE instructions could be  
substituted for the scalar operations above. (Both n, m and # of  
parameters will be compile-time constants, so no runtime jiggling of  
opcodes need be done.)

Questions:

1.    Name of these functions? Interleave/deinterleave, splice/ 
desplice/unsplice, transpose/detranspose/retranspose (???), merge/ 
unmerge/demerge etc.? Something short, succinct and similar enough to  
existing usage (LISP, other languages, matrix libraries) would be good.
2.    What should the syntax of deinterleave be?
     Should it be as above i.e. deinterleave <n, m> (v)
     or more similar to other sorts of valarray subsetting operations  
e.g. v [deinterleave <n, m> ()]


Cheers, Glen Low


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