Subj : Re: Faster matrix permutation algorithm?
To   : comp.lang.c,comp.programming
From : russell kym horsell
Date : Sun Aug 14 2005 04:23 am

In comp.lang.c Jack Middleton <bitbucket@mirafor.com> wrote:
> Hi!
> I'm lookin for a faster permutation algorithm for matrices. I know that 
> it can be done with multiplying a matrix with a permutation matrix. It 
> just seems a waste to iterate through all those zeroes. Is there an 
> algorithm for matrixes that is optimized just for permutations? The 
> matrices that I use are fairly small (around 6*6) and I only use 
> positive integers as elements.
[...]


If you want to permute rows/cols (or both) then you can simply iterate
through one or more maps/indexes.  Manipulate the maps directly and
only use them as indexes at the last second.


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