/* nag_dgbtrs (f07bec) Example Program.
 *
 * Copyright 2001 Numerical Algorithms Group.
 *
 * Mark 7, 2001.
 */

#include <stdio.h>
#include <nag.h>
#include <nag_stdlib.h>
#include <nagf07.h>
#include <nagx04.h>

int main(void)
{
  /* Scalars */
  Integer       i, ipiv_len, j, kl, ku, n, nrhs, pdab, pdb;
  Integer       exit_status = 0;
  NagError      fail;
  Nag_OrderType order;

  /* Arrays */
  double        *ab = 0, *b = 0;
  Integer       *ipiv = 0;

#ifdef NAG_COLUMN_MAJOR
#define AB(I, J) ab[(J-1)*pdab + kl + ku + I - J]
#define B(I, J)  b[(J-1)*pdb + I - 1]
  order = Nag_ColMajor;
#else
#define AB(I, J) ab[(I-1)*pdab + kl + J - I]
#define B(I, J)  b[(I-1)*pdb + J - 1]
  order = Nag_RowMajor;
#endif

  INIT_FAIL(fail);

  printf("nag_dgbtrs (f07bec) Example Program Results\n\n");

  /* Skip heading in data file */
  scanf("%*[^\n] ");
  scanf("%ld%ld%ld%ld%*[^\n] ", &n, &nrhs,
         &kl, &ku);
  ipiv_len = n;
#ifdef NAG_COLUMN_MAJOR
  pdab = 2*kl + ku + 1;
  pdb = n;
#else
  pdab = 2*kl + ku + 1;
  pdb = nrhs;
#endif

  /* Allocate memory */
  if (!(ab = NAG_ALLOC((2*kl+ku+1) * n, double)) ||
      !(b = NAG_ALLOC(nrhs * n, double)) ||
      !(ipiv = NAG_ALLOC(ipiv_len, Integer)))
    {
      printf("Allocation failure\n");
      exit_status = -1;
      goto END;
    }

  /* Read A from data file */
  for (i = 1; i <= n; ++i)
    {
      for (j = MAX(i-kl, 1); j <= MIN(i+ku, n); ++j)
        scanf("%lf", &AB(i, j));
    }
  scanf("%*[^\n] ");
  /* Read B from data file */
  for (i = 1; i <= n; ++i)
    {
      for (j = 1; j <= nrhs; ++j)
        scanf("%lf", &B(i, j));
    }
  scanf("%*[^\n] ");

  /* Factorize A */
  /* nag_dgbtrf (f07bdc).
   * LU factorization of real m by n band matrix
   */
  nag_dgbtrf(order, n, n, kl, ku, ab, pdab, ipiv, &fail);
  if (fail.code != NE_NOERROR)
    {
      printf("Error from nag_dgbtrf (f07bdc).\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }
  /* Compute solution */
  /* nag_dgbtrs (f07bec).
   * Solution of real band system of linear equations,
   * multiple right-hand sides, matrix already factorized by
   * nag_dgbtrf (f07bdc)
   */
  nag_dgbtrs(order, Nag_NoTrans, n, kl, ku, nrhs, ab, pdab, ipiv,
             b, pdb, &fail);
  if (fail.code != NE_NOERROR)
    {
      printf("Error from nag_dgbtrs (f07bec).\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }
  /* Print solution */
  /* nag_gen_real_mat_print (x04cac).
   * Print real general matrix (easy-to-use)
   */
  fflush(stdout);
  nag_gen_real_mat_print(order, Nag_GeneralMatrix, Nag_NonUnitDiag, n, nrhs, b,
                         pdb, "Solution(s)", 0, &fail);
  if (fail.code != NE_NOERROR)
    {
      printf("Error from nag_gen_real_mat_print (x04cac).\n%s\n",
              fail.message);
      exit_status = 1;
      goto END;
    }
 END:
  if (ab) NAG_FREE(ab);
  if (b) NAG_FREE(b);
  if (ipiv) NAG_FREE(ipiv);
  return exit_status;
}