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From: | David Bateman |
Subject: | Re: nnz and char |
Date: | Tue, 31 Jan 2006 16:14:19 +0100 |
User-agent: | Mozilla Thunderbird 0.8 (X11/20040923) |
Andy Adler wrote:
In a compressed column sparse storage the actual number of elements stored in the matrix is cidx[ncol] where as the amount of memory actually allocated to store the elements might differ from this value. Within octave this doesn't cause a problem as the two always match. However, I have had matrices imported from matlab where this was not the case and that caused me much pain...On Tue, 31 Jan 2006, David Bateman wrote:> This patch is not quite right. The problem is that there are two methods> in Sparse<T> for the number of non-zero elements. These are "nnz" and > "nonzero". "nnz" returns the size of data and ridx, while nonzero > returns "cidx[ncol]"... For matlab compatiablity for sparse matrices, > Fnnz should return "cidx[ncol]" rather than the size of ridx and data, > which is why the old Fnnz in sparse.cc used the "nonzero" method of > Sparse<T>.. David, I'm embarassed to admit this, but I can't figure out what you said. Could you explain what the difference is between cidx[ncol] and length( ridx )? -- Andy Adler <address@hidden> 1(613)562-5800x6218
D. -- David Bateman address@hiddenMotorola Labs - Paris +33 1 69 35 48 04 (Ph) Parc Les Algorithmes, Commune de St Aubin +33 6 72 01 06 33 (Mob) 91193 Gif-Sur-Yvette FRANCE +33 1 69 35 77 01 (Fax) The information contained in this communication has been classified as: [x] General Business Information [ ] Motorola Internal Use Only [ ] Motorola Confidential Proprietary
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