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Saving memory in spones()
From: |
John W. Eaton |
Subject: |
Saving memory in spones() |
Date: |
Fri, 13 May 2011 13:02:33 -0400 |
On 12-May-2011, Rik wrote:
| 5/12/11
|
| The spones() function returns a sparse matrix with a 1 in each non-zero
| entry in the matrix. It is useful for viewing the structure of a matrix,
| but obviously all of the actual values are lost.
|
| The code is simple enough to quote in its entirety:
|
| [i, j, v] = find (S);
| [m, n] = size (S);
|
| r = sparse (i, j, 1, m, n);
|
| Question: Why not return a sparse logical matrix rather than a sparse
| double matrix and save 7 bytes per entry?
|
| r = sparse (i, j, logical (1), m, n);
The spones function also exists in Matlab and it apparently returns a
sparse matrix with class double. I suppose it could cause some
compatibility problems if Octave behaved differently.
jwe