[PATCH 0 of 4] Permutation matrices: One bugfix, one enhancement, sparse-perm ops, and a use in lu().

John W. Eaton jwe at octave.org
Tue Mar 10 23:51:33 CDT 2009


On 10-Mar-2009, Jason Riedy wrote:

| The bugfix:
|   * Make the column permutation vector in sparse LU cols()-long.
| 
| The simple enhancement:
|   * Add an override to Octave's find() for permutation matrices.
| Seems odd that find takes O(n^2) time on permutation matrices.  IIRC,
| it's the only operation to convert a perm. matrix to a perm. vector.
| 
| The operations:
|   * Add perm * sparse, perm \ sparse, sparse * perm, and sparse / perm operations.
| There might be a way to use the existing indexing ops, but I couldn't
| see it.
| 
| And a future use in lu:
|   * sparse-perm-ops Have sparse LU return permutation matrices rather than sparse matrices.
| This last one is included mostly because it flushed out the bug, but
| it is a thought for the future.

Did you intend to include a changeset with this message?

jwe


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