MathGroup Archive 2000

[Date Index] [Thread Index] [Author Index]

Search the Archive

Efficient Replacement Rules to Matrix?


What is the most efficient (in terms of time) method to transform a set
of replacement rules to a matrix.  For example, I have:

matrix = ZeroMatrix[5];
repmat = {{1, 1} -> 4., {5, 5} -> 3,{4, 4} -> 10,{2, 2} -> 2 + I 6, {3,
3} -> 40.};

and I transfor to a matrix thus:

matrix = ReplacePart[matrix, Sequence @@ #]) & /@ (
      {Last[#], #[[1]]} & /@ matrix);

But for large matrices this is quite slow!  Is there a more efficient
method?

I then will form a matrix product with this sparse matrix:
result= matrix.avector and this is indeed my goal.

I would appreciate any ideas on this matter.
Many thanks!

-Roger Jones

PS This comes to light in the context of using the new Mathematica
function "SparseLinearSolve"



  • Prev by Date: Option ExcludedForms
  • Next by Date: Re: Product with p!=j
  • Previous by thread: Option ExcludedForms
  • Next by thread: Re: Efficient Replacement Rules to Matrix?