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Re: Sparse matrix algorithms [message #28288 is a reply to message #28281]

Fri, 30 November 2001 03:54

the_cacc
Messages: 104
Registered: October 2001

Senior Member

Hi,

I had this experience a few weeks ago. The NR code is for NxN only so
I doubt IDL will generalize to NxM on their own. I wrote to NR
suggesting they publish NxM sparse algorithms and they gave a very
positive response so expect them to be available next edition of the
book.

In the meantime, the penalty for expanding your NxM to MxM (assuming
M>N) in sparse format is M-N additional zeros (ie. those on the
diagonal). I found this quite acceptable for my matrices: 64000 x
128000 with around 10^6 non-zero entries. So I have to store 64000
zeros unnecessarily.

You will have to write your own version of sprsin to deal with this,
although since you probably won't be able to store your full matrix in
memory you'll need to do this anyway.

Ciao.

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[Message index]

		Re: Sparse matrix algorithms By: Ralf Flicker on Fri, 30 November 2001 11:28
		Re: Sparse matrix algorithms By: the_cacc on Fri, 30 November 2001 03:54
		Re: Sparse matrix algorithms By: the_cacc on Mon, 03 December 2001 06:56

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