/* nag_dgtsvx (f07cbc) Example Program.
 *
 * Copyright 2017 Numerical Algorithms Group.
 *
 * Mark 26.1, 2017.
 */

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

int main(void)
{

  /* Scalars */
  double rcond;
  Integer exit_status = 0, i, j, n, nrhs, pdb, pdx;

  /* Arrays */
  double *b = 0, *berr = 0, *d = 0, *df = 0, *dl = 0, *dlf = 0, *du = 0;
  double *du2 = 0, *duf = 0, *ferr = 0, *x = 0;
  Integer *ipiv = 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_dgtsvx (f07cbc) Example Program Results\n\n");
  /* Skip heading in data file */
  scanf("%*[^\n]");
  scanf("%" NAG_IFMT "%" NAG_IFMT "%*[^\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)) ||
      !(berr = NAG_ALLOC(nrhs, double)) ||
      !(d = NAG_ALLOC(n, double)) ||
      !(df = NAG_ALLOC(n, double)) ||
      !(dl = NAG_ALLOC(n - 1, double)) ||
      !(dlf = NAG_ALLOC(n - 1, double)) ||
      !(du = NAG_ALLOC(n - 1, double)) ||
      !(du2 = NAG_ALLOC(n - 2, double)) ||
      !(duf = NAG_ALLOC(n - 1, double)) ||
      !(ferr = NAG_ALLOC(nrhs, double)) ||
      !(x = NAG_ALLOC(n * nrhs, double)) || !(ipiv = NAG_ALLOC(n, Integer)))
  {
    printf("Allocation failure\n");
    exit_status = -1;
    goto END;
  }
#ifdef NAG_COLUMN_MAJOR
  pdb = n;
  pdx = n;
#else
  pdb = nrhs;
  pdx = nrhs;
#endif
  /* Read the tridiagonal matrix A from data file */
  for (i = 0; i < n - 1; ++i)
    scanf("%lf", &du[i]);
  scanf("%*[^\n]");
  for (i = 0; i < n; ++i)
    scanf("%lf", &d[i]);
  scanf("%*[^\n]");
  for (i = 0; i < n - 1; ++i)
    scanf("%lf", &dl[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]");

  /* Solve the equations AX = B using nag_dgtsvx (f07cbc). */
  nag_dgtsvx(order, Nag_NotFactored, Nag_NoTrans, n, nrhs, dl, d, du, dlf, df,
             duf, du2, ipiv, b, pdb, x, pdx, &rcond, ferr, berr, &fail);
  if (fail.code != NE_NOERROR && fail.code != NE_SINGULAR) {
    printf("Error from nag_dgtsvx (f07cbc).\n%s\n", fail.message);
    exit_status = 1;
    goto END;
  }

  /* Print solution using nag_gen_real_mat_print (x04cac). */
  fflush(stdout);
  nag_gen_real_mat_print(order, Nag_GeneralMatrix, Nag_NonUnitDiag, n, nrhs,
                         x, pdx, "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;
  }

  /* Print solution, error bounds and condition number */
  printf("\nBackward errors (machine-dependent)\n");
  for (j = 0; j < nrhs; ++j)
    printf("%11.1e%s", berr[j], j % 7 == 6 ? "\n" : " ");

  printf("\n\nEstimated forward error bounds (machine-dependent)\n");
  for (j = 0; j < nrhs; ++j)
    printf("%11.1e%s", ferr[j], j % 7 == 6 ? "\n" : " ");

  printf("\n\nEstimate of reciprocal condition number\n%11.1e\n", rcond);
  if (fail.code == NE_SINGULAR)
    printf("Error from nag_dgtsvx (f07cbc).\n%s\n", fail.message);
END:
  NAG_FREE(b);
  NAG_FREE(berr);
  NAG_FREE(d);
  NAG_FREE(df);
  NAG_FREE(dl);
  NAG_FREE(dlf);
  NAG_FREE(du);
  NAG_FREE(du2);
  NAG_FREE(duf);
  NAG_FREE(ferr);
  NAG_FREE(x);
  NAG_FREE(ipiv);

  return exit_status;
}

#undef B