Re: [Help-gsl] Copy matrix from the one do not has tda to the other one that has tda

[Francesco Abbate]

2012/1/10 liufenglai <address@hidden>:
> Hi Everyone,
>
> I constructed several matrices, one of them has tda and is imported from
> the outside data:
> gsl_matrix_view M1 =  gsl_matrix_view_array_with_tda(M,row,col,ld);
> I also constructed a gsl_matrix named as M2;
> gsl_matrix* M2 = gsl_matrix_alloc(row,col);
> after some calculations I want to copy the data in M2 back to the M1.
> However, M1 could be some submatrix of the original one, and M2 is some
> full matrix. I am going to call the gsl_matrix_memcpy, I do not whether
> it will takes care of the situation above?

Hi,

all the GSL matrix functions are safe to be used in any matrix, the
tda will always be taken into account correctly.

Here the code that perform the matrix copy:
int
FUNCTION (gsl_matrix, memcpy) (TYPE (gsl_matrix) * dest,
                               const TYPE (gsl_matrix) * src)
{
  const size_t src_size1 = src->size1;
  const size_t src_size2 = src->size2;
  const size_t dest_size1 = dest->size1;
  const size_t dest_size2 = dest->size2;

  if (src_size1 != dest_size1 || src_size2 != dest_size2)
    {
      GSL_ERROR ("matrix sizes are different", GSL_EBADLEN);
    }

  {
    const size_t src_tda = src->tda ;
    const size_t dest_tda = dest->tda ;
    size_t i, j;

    for (i = 0; i < src_size1 ; i++)
      {
        for (j = 0; j < MULTIPLICITY * src_size2; j++)
          {
            dest->data[MULTIPLICITY * dest_tda * i + j]
              = src->data[MULTIPLICITY * src_tda * i + j];
          }
      }
  }

  return GSL_SUCCESS;
}

As you can see the tda is taken into account for both the source and
destination matrix.

Best regards,
Francesco