Re: [Help-gsl] Help with GSL Matrices

[adarsh]

Thanks James. That helps.

I have few more questions:

1. How can we determine if a gsl matrix is free or not?

2. Does gsl_matrix_swap_rows work by copying memory or by some other
(possibly similar to pointer in spirit) mechanism.

Thanks,
Adarsh


>> I have two gsl matrices, say A & B. I want to free the memory in A, and
>> then make A owner of contents of B and free (name) B for further
>> allocation. I am wondering if this is possible in the current
>> architecture
>> without memcpy?
>
>> If yes, can someone send me a small code snippet that would achieve the
>> same.
>
> matrix->block is the memory block that stores the values
> matrix->owner is an integer that indicates whether the block should be
> freed with the matrix
>
> gsl_matrix * A = gsl_matrix_alloc(1,1);
> gsl_matrix * B = gsl_matrix_alloc(9,9);
>
> assert(A->owner);
> assert(B->owner);
>
> gsl_block_free(A->block);  //free A's memory block without freeing A
> A->block = B->block;       //A takes ownership of B's block
> A->data = B->data;         //A points into B's block
> B->owner = 0;              //B is relieved of ownership
> gsl_matrix_free(B);        //B is free'd, but his block isn't
>
>
>
>
> --
> James Bergstra
> http://www-etud.iro.umontreal.ca/~bergstrj
>
>
>
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