Re: [Help-gsl] gsl_blas_dtrsm

[Brian Gough]

Remi Vieux writes:
 > Does the matrix A has to be triangular to use this function? What
 > exactly is TransA for? Same question for the parameter Diag: what do you
 > mean by "the diagonal of A is used or taken as unity"?

Hello,

The BLAS tr functions only work with triangular matrices.

I suggest taking an LU decomposition of A and solving in place
on the columns of B. e.g.

  gsl_linalg_LU_decomp(A,p,&s);

  for (j = 0; j < B->size2 ;j++) {
    gsl_vector_view x = gsl_matrix_column (B, j);
    gsl_linalg_LU_svx (A, p, &x.vector);
  }

See the manual for details of the functions involved.

-- 
Brian Gough

Network Theory Ltd,
Publishing the GSL Manual - http://www.network-theory.co.uk/gsl/manual/