🚀 go-pugleaf

In article <17n6fjINNhvt@network.ucsd.edu> mbk@lyapunov.ucsd.edu (Matt Kennel) writes:
   I have no idea what Mr Rubin really wants but here are a couple of 
   easy ones of the top of my head:

    P, D, Q <- singular_value_decomposition(A);

How about :-

(p,d,q) = singular_value_decomposition A


   Array index notation:

   for all i <= j: a(i,j) <- sum over (k) ( b(i,k)*c(j,N,k) )

I'm not _exactly_ sure what the above does (e.g. is N constant?), so
the following may be wrong (but it is better than my previous attempt
which I hopefully cancelled correctly :-)

foo b c = array bds vs
  where
    vs = [ (i,j) := f i j | (i,j) <- range bds, i <= j ]
    f i j = sum [ b!(i,k)*c!(j,n,k) | k <- range (klb,kub) ]
    bds = ((ilb,jlb),(iub,jub))
    ((ilb,klb),(iub,kub)) = bounds b
    ((jlb,_,_),(jub,n,_)) = bounds c

An alternative (and possibly more efficient) version of _vs_ is :-

  vs = [ (i,j) := f i j | i <- range (ilb,iub), j <- range (i,jub) ]

Note this is untested as I currently don't have a compiler installed.
As to the notation, I'll do you a deal: you explain the one you're
using and I'll explain the one I'm using :-)


   I won't bore you with the obvious complex numbers, exponentiation, etc.

Why not, you may be pleasantly suprised.

bevan