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## Re: [Help-gsl] Multiple views on same matrix

**From**: |
Brian Gough |

**Subject**: |
Re: [Help-gsl] Multiple views on same matrix |

**Date**: |
Wed, 23 Jan 2008 21:53:11 +0000 |

**User-agent**: |
Wanderlust/2.14.0 (Africa) Emacs/22.1 Mule/5.0 (SAKAKI) |

At Tue, 22 Jan 2008 23:22:51 -0500,
Michael Braun wrote:
>* For example, is this a legal representation:*
>* *
>* gsl_matrix * A = gsl_matrix_alloc(3,6);*
>* gsl_matrix_view V1 = gsl_matrix_submatrix(A,0,0,2,6);*
>* gsl_matrix_view V2 = gsl_matrix_submatrix(A,0,0,2,4); // the views overlap*
>* gsl_matrix_memcpy(&V1.matrix,X); / X is a 2x6 matrix*
>* *
>* And then, could I set, get and memcpy to &V1.matrix and &V2.matrix freely?*
>* Or, once I create V2, does V1 disappear?*
There can be multiple views of the same matrix, it is not a problem.
>* 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?*
Using gsl functions alone should not cause any error, they all verify
that the (sub)matrices are valid when they are called.
To find unexplained segmentation faults:
1. eliminate compiler warnings
(http://www.network-theory.co.uk/docs/gccintro/gccintro_10.html)
2. try runing the program under "valgrind" (www.valgrind.org)
--
Brian Gough