/* nag_dtbrfs (f07vhc) 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, j, k, kd, n, nrhs, pdab, pdb, pdx;
  Integer  ferr_len, berr_len;
  Integer  exit_status=0;
  Nag_UploType uplo_enum;
  NagError fail;
  Nag_OrderType order;

  /* Arrays */
  char    uplo[2];
  double  *ab=0, *b=0, *berr=0, *ferr=0, *x=0;

#ifdef NAG_COLUMN_MAJOR
#define AB_UPPER(I,J) ab[(J-1)*pdab + k + I - J - 1]
#define AB_LOWER(I,J) ab[(J-1)*pdab + I - J]
#define B(I,J) b[(J-1)*pdb + I - 1]
#define X(I,J) x[(J-1)*pdx + I - 1]
  order = Nag_ColMajor;
#else
#define AB_UPPER(I,J) ab[(I-1)*pdab + J - I]
#define AB_LOWER(I,J) ab[(I-1)*pdab + k + J - I - 1]
#define B(I,J) b[(I-1)*pdb + J - 1]
#define X(I,J) x[(I-1)*pdx + J - 1]
  order = Nag_RowMajor;
#endif

  INIT_FAIL(fail);
  Vprintf("nag_dtbrfs (f07vhc) Example Program Results\n\n");

  /* Skip heading in data file */
  Vscanf("%*[^\n] ");
  Vscanf("%ld%ld%ld%*[^\n] ", &n, &kd, &nrhs);
  pdab = kd + 1;
#ifdef NAG_COLUMN_MAJOR
  pdb = n;
  pdx = n;
#else
  pdb = nrhs;
  pdx = nrhs;
#endif


  ferr_len = nrhs;
  berr_len = nrhs;

  /* Allocate memory */
  if ( !(berr = NAG_ALLOC(berr_len, double)) ||
       !(ferr = NAG_ALLOC(ferr_len, double)) ||
       !(ab = NAG_ALLOC((kd+1) * n, double)) ||
       !(b = NAG_ALLOC(n * nrhs, double)) ||
       !(x = NAG_ALLOC(n * nrhs, double)) )
    {
      Vprintf("Allocation failure\n");
      exit_status = -1;
      goto END;
    }

  /* Read A and B from data file, and copy B to X */
  Vscanf(" ' %1s '%*[^\n] ", uplo);
  if (*(unsigned char *)uplo == 'L')
    uplo_enum = Nag_Lower;
  else if (*(unsigned char *)uplo == 'U')
    uplo_enum = Nag_Upper;
  else
    {
      Vprintf("Unrecognised character for Nag_UploType type\n");
      exit_status = -1;
      goto END;
    }
  k = kd + 1;
  if (uplo_enum == Nag_Upper)
    {
      for (i = 1; i <= n; ++i)
        {
          for (j = i; j <= MIN(i+kd,n); ++j)
            Vscanf("%lf", &AB_UPPER(i,j));
        }
      Vscanf("%*[^\n] ");
    }
  else
    {
      for (i = 1; i <= n; ++i)
        {
          for (j = MAX(1,i-kd); j <= i; ++j)
            Vscanf("%lf", &AB_LOWER(i,j));
        }
      Vscanf("%*[^\n] ");
    }

  for (i = 1; i <= n; ++i)
    {
      for (j = 1; j <= nrhs; ++j)
        Vscanf("%lf", &B(i,j));
    }
  Vscanf("%*[^\n] ");
  /* Copy B to X */
  for (i = 1; i <= n; ++i)
    {
      for (j = 1; j <= nrhs; ++j)
        X(i,j) = B(i,j);
    }
  /* Compute solution in the array X */
  /* nag_dtbtrs (f07vec).
   * Solution of real band triangular system of linear
   * equations, multiple right-hand sides
   */
  nag_dtbtrs(order, uplo_enum, Nag_NoTrans, Nag_NonUnitDiag, n,
             kd, nrhs, ab, pdab, x, pdx, &fail);
  if (fail.code != NE_NOERROR)
    {
      Vprintf("Error from nag_dtbtrs (f07vec).\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }
  /* Improve solution, and compute backward errors and */
  /* estimated bounds on the forward errors */
  /* nag_dtbrfs (f07vhc).
   * Error bounds for solution of real band triangular system
   * of linear equations, multiple right-hand sides
   */
  nag_dtbrfs(order, uplo_enum, Nag_NoTrans, Nag_NonUnitDiag, n,
             kd, nrhs, ab, pdab, b, pdb, x, pdx, ferr, berr, &fail);
  if (fail.code != NE_NOERROR)
    {
      Vprintf("Error from nag_dtbrfs (f07vhc).\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }
  /* Print details of solution */

  /* nag_gen_real_mat_print (x04cac).
   * Print real general matrix (easy-to-use)
   */
  nag_gen_real_mat_print(order, Nag_GeneralMatrix, Nag_NonUnitDiag, n, nrhs,
                         x, pdx, "Solution(s)", 0, &fail);
  if (fail.code != NE_NOERROR)
    {
      Vprintf("Error from nag_gen_real_mat_print (x04cac).\n%s\n",
              fail.message);
      exit_status = 1;
      goto END;
    }
  Vprintf("\nBackward errors (machine-dependent)\n");
  for (j = 1; j <= nrhs; ++j)
    Vprintf("%11.1e%s", berr[j-1], j%7==0 ?"\n":" ");
  Vprintf("\nEstimated forward error bounds "
          "(machine-dependent)\n");
  for (j = 1; j <= nrhs; ++j)
    Vprintf("%11.1e%s", ferr[j-1], j%7==0 ?"\n":" ");
  Vprintf("\n");
 END:
  if (berr) NAG_FREE(berr);
  if (ferr) NAG_FREE(ferr);
  if (ab) NAG_FREE(ab);
  if (b) NAG_FREE(b);
  if (x) NAG_FREE(x);
  return exit_status;
}