/* nag_dpprfs (f07ghc) 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, n, nrhs, ap_len, afp_len, pdb, pdx, ferr_len, berr_len;
  Integer  exit_status=0;
  NagError fail;
  Nag_UploType uplo_enum;
  Nag_OrderType order;
  /* Arrays */
  char   uplo[2];
  double *afp=0, *ap=0, *b=0, *berr=0, *ferr=0, *x=0;

#ifdef NAG_COLUMN_MAJOR
#define A_UPPER(I,J) ap[J*(J-1)/2 + I - 1]
#define A_LOWER(I,J) ap[(2*n-J)*(J-1)/2 + I - 1]
#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 A_LOWER(I,J) ap[I*(I-1)/2 + J - 1]
#define A_UPPER(I,J) ap[(2*n-I)*(I-1)/2 + J - 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("f07ghc Example Program Results\n\n");
  /* Skip heading in data file */
  Vscanf("%*[^\n] ");
  Vscanf("%ld%ld%*[^\n] ", &n, &nrhs);
  ap_len = n * (n + 1)/2;
  afp_len = n * (n + 1)/2;
#ifdef NAG_COLUMN_MAJOR
  pdb = n;
  pdx = n;
#else
  pdb = nrhs;
  pdx = nrhs;
#endif

  ferr_len = nrhs;
  berr_len = nrhs;

  /* Allocate memory */
  if ( !(afp = NAG_ALLOC(ap_len, double)) ||
       !(ap = NAG_ALLOC(afp_len, double)) ||
       !(b = NAG_ALLOC(n * nrhs, double)) ||
       !(berr = NAG_ALLOC(berr_len, double)) ||
       !(ferr = NAG_ALLOC(ferr_len, 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 A to AFP and 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;
    }
  if (uplo_enum == Nag_Upper)
    {
      for (i = 1; i <= n; ++i)
        {
          for (j = i; j <= n; ++j)
            Vscanf("%lf", &A_UPPER(i,j));
        }
      Vscanf("%*[^\n] ");
    }
  else
    {
      for (i = 1; i <= n; ++i)
        {
          for (j = 1; j <= i; ++j)
            Vscanf("%lf", &A_LOWER(i,j));
        }
      Vscanf("%*[^\n] ");
    }
  for (i = 1; i <= n; ++i)
    {
      for (j = 1; j <= nrhs; ++j)
        Vscanf("%lf", &B(i,j));
    }
  Vscanf("%*[^\n] ");
  for (i = 0; i < n * (n + 1) / 2; ++i)
    afp[i] = ap[i];
  for (i = 1; i <= n; ++i)
    {
      for (j = 1; j <= nrhs; ++j)
        X(i,j) = B(i,j);
    }
  /* Factorize A in the array AFP */
  f07gdc(order, uplo_enum, n, afp, &fail);
  if (fail.code != NE_NOERROR)
    {
      Vprintf("Error from f07gdc.\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }
  /* Compute solution in the array X */
  f07gec(order, uplo_enum, n, nrhs, afp, x, pdx, &fail);
  if (fail.code != NE_NOERROR)
    {
      Vprintf("Error from f07gec.\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }
  /* Improve solution, and compute backward errors and */
  /* estimated bounds on the forward errors */
  f07ghc(order, uplo_enum, n, nrhs, ap, afp, b, pdb, x, pdx, ferr, berr,
         &fail);
  if (fail.code != NE_NOERROR)
    {
      Vprintf("Error from f07ghc.\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }
  /* Print solution */
  x04cac(order, Nag_GeneralMatrix, Nag_NonUnitDiag, n, nrhs, x, pdx,
         "Solution(s)", 0, &fail);
  if (fail.code != NE_NOERROR)
    {
      Vprintf("Error from 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 (afp) NAG_FREE(afp);
  if (ap) NAG_FREE(ap);
  if (b) NAG_FREE(b);
  if (berr) NAG_FREE(berr);
  if (ferr) NAG_FREE(ferr);
  if (x) NAG_FREE(x);
  return exit_status;
}