/* nag_dpttrs (f07jec) Example Program.
 *
 * Copyright 2004 Numerical Algorithms Group.
 *
 * Mark 23, 2011.
 */

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

int main(void)
{
  /* Scalars */
  Integer       exit_status = 0, i, j, n, nrhs, pdb;

  /* Arrays */
  double        *b = 0, *d = 0, *e = 0;

  /* Nag Types */
  NagError      fail;
  Nag_OrderType order;

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

  INIT_FAIL(fail);

  printf("nag_dpttrs (f07jec) Example Program Results\n\n");
  /* Skip heading in data file */
  scanf("%*[^\n]");

  scanf("%ld%ld%*[^\n]", &n, &nrhs);
  if (n < 0 || nrhs < 0)
    {
      printf("Invalid n or nrhs\n");
      exit_status = 1;
      goto END;
    }
  /* Allocate memory */
  if (!(b = NAG_ALLOC(n * nrhs, double)) ||
      !(d = NAG_ALLOC(n, double)) ||
      !(e = NAG_ALLOC(n-1, double)))
    {
      printf("Allocation failure\n");
      exit_status = -1;
      goto END;
    }
#ifdef NAG_COLUMN_MAJOR
  pdb = n;
#else
  pdb = nrhs;
#endif

  /* Read the upper bidiagonal part of the tridiagonal matrix A from */
  /* data file */
  for (i = 0; i < n - 1; ++i) scanf("%lf", &e[i]);
  scanf("%*[^\n]");
  for (i = 0; i < n; ++i) scanf("%lf", &d[i]);
  scanf("%*[^\n]");

  /* Read the right hand matrix B */
  for (i = 1; i <= n; ++i)
    for (j = 1; j <= nrhs; ++j) scanf("%lf", &B(i, j));
  scanf("%*[^\n]");

  /* Factorize the tridiagonal matrix A using nag_dpttrf (f07jdc). */
  nag_dpttrf(n, d, e, &fail);
  if (fail.code != NE_NOERROR)
    {
      printf("Error from nag_dpttrf (f07jdc).\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }

  /* Solve the equations AX = B using nag_dpttrs (f07jec). */
  nag_dpttrs(order, n, nrhs, d, e, b, pdb, &fail);
  if (fail.code != NE_NOERROR)
    {
      printf("Error from nag_dpttrs (f07jec).\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }

  /* Print the solution using nag_gen_real_mat_print (x04cac). */

  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 (b) NAG_FREE(b);
  if (d) NAG_FREE(d);
  if (e) NAG_FREE(e);

  return exit_status;
}

#undef B