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[Help-gsl] Matrix views and column swapping

From: Michael Braun
Subject: [Help-gsl] Matrix views and column swapping
Date: Tue, 22 Jan 2008 20:32:24 -0500

Hi.  I have a strange problem that is causing a segfault, and I have a
theory about the cause.  Hopefully someone on this list can confirm/disprove
this theory.

I have a matrix A, and a view V on a submatrix of A.  I then swap two
columns of A.  Later, I copy another submatrix B into V (and, in turn,
changing values in A).  Is V a view on the same column indices of A as
before?  Is it possible that copying B into V after the swap in A is causing
some kind of memory problem?

To give you an idea of the kind of thing I am talking about, consider the
following code (where X is a previously defined 3x3 matrix):

gsl_matrix * A = gsl_matrix_alloc(3,5);
gsl_matrix_view V = gsl_matrix_submatrix(A,0,0,3,3);
gsl_matrix_swap_columns(A, 1, 4);
gsl_matrix_memcpy(&V.matrix, X);

Thanks for your help.


Michael Braun
Assistant Professor of Marketing
MIT Sloan School of Management
One Amherst St., E40-169
Cambridge, MA 02142
(617) 253-3436

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