/* nag_zptrfs (f07jvc) 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>
#include <nagf16.h>

int main(void)
{

  /* Scalars */
  Integer       exit_status = 0, i, j, n, nrhs, pdb, pdx;
  Nag_OrderType order;

  /* Arrays */
  Complex       *b = 0, *e = 0, *ef = 0, *x = 0;
  double        *berr = 0, *d = 0, *df = 0, *ferr = 0;

  /* Nag Types */
  NagError      fail;

#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_zptrfs (f07jvc) 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;
    }
  if (!(b    = NAG_ALLOC(n * nrhs, Complex)) ||
      !(e    = NAG_ALLOC(n - 1, Complex)) ||
      !(ef   = NAG_ALLOC(n - 1, Complex)) ||
      !(x    = NAG_ALLOC(n * nrhs, Complex)) ||
      !(berr = NAG_ALLOC(nrhs, double)) ||
      !(d    = NAG_ALLOC(n, double)) ||
      !(df   = NAG_ALLOC(n, double)) ||
      !(ferr = NAG_ALLOC(nrhs, double)))
    {
      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 lower bidiagonal part of the tridiagonal matrix A from */
  /* data file */
  for (i = 0; i < n; ++i) scanf("%lf", &d[i]);
  scanf("%*[^\n]");
  for (i = 0; i < n - 1; ++i) scanf(" ( %lf , %lf )", &e[i].re, &e[i].im);
  scanf("%*[^\n]");

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

  /* Copy A into DF and EF, and copy B into X */
  for (i = 0; i < n; ++i) df[i] = d[i];
  for (i = 0; i < n - 1; ++i) {
    ef[i].re = e[i].re; 
    ef[i].im = e[i].im;
  }

  /* Copy B into X using nag_zge_copy (f16tfc). */
  nag_zge_copy(order, Nag_NoTrans, n, nrhs, b, pdb, x, pdx, &fail);
  if (fail.code != NE_NOERROR)
    {
      printf("Error from nag_zge_copy (f16tfc).\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }

  /* Factorize the copy of the tridiagonal matrix A 
   * using nag_zpttrf (f07jrc). 
   */
  nag_zpttrf(n, df, ef, &fail);
  if (fail.code != NE_NOERROR)
    {
      printf("Error from nag_zpttrf (f07jrc).\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }

  /* Solve the equations AX = B using nag_zpttrs (f07jsc). */
  nag_zpttrs(order, Nag_Lower, n, nrhs, df, ef, x, pdx, &fail);
  if (fail.code != NE_NOERROR)
    {
      printf("Error from nag_zpttrs (f07jsc).\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }

  /* Improve the solution and compute error estimates 
   * using nag_zptrfs (f07jvc).
   */
  nag_zptrfs(order, Nag_Lower, n, nrhs, d, e, df, ef, b, pdb, x, pdx,
             ferr, berr, &fail);
  if (fail.code != NE_NOERROR)
    {
      printf("Error from nag_zptrfs (f07jvc).\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }

  /* Print the solution using nag_gen_complx_mat_print_comp (x04dbc). */
  fflush(stdout);
  nag_gen_complx_mat_print_comp(order, Nag_GeneralMatrix, Nag_NonUnitDiag, n,
                                nrhs, x, pdx, Nag_BracketForm, "%7.4f",
                                "Solution(s)", Nag_IntegerLabels, 0,
                                Nag_IntegerLabels, 0, 80, 0, 0, &fail);
  if (fail.code != NE_NOERROR)
    {
      printf("Error from nag_gen_complx_mat_print_comp (x04dbc).\n%s\n",
             fail.message);
      exit_status = 1;
      goto END;
    }

  /* Print the the forward and backward error estimates */
  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":" ");

 END:
  if (b)    NAG_FREE(b);
  if (e)    NAG_FREE(e);
  if (ef)   NAG_FREE(ef);
  if (x)    NAG_FREE(x);
  if (berr) NAG_FREE(berr);
  if (d)    NAG_FREE(d);
  if (df)   NAG_FREE(df);
  if (ferr) NAG_FREE(ferr);

  return exit_status;
}
#undef B