/* 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(int argc, char *argv[])
{
  FILE          *fpin, *fpout;
  char          *outfile = 0;
  /* 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;
  Nag_OrderType order;
  /* Arrays */
  char          nag_enum_arg[40];
  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);

  /* Check for command-line IO options */
  fpin = nag_example_file_io(argc, argv, "-data", NULL);
  fpout = nag_example_file_io(argc, argv, "-results", NULL);
  (void) nag_example_file_io(argc, argv, "-nag_write", &outfile);
  fprintf(fpout, "nag_dpprfs (f07ghc) Example Program Results\n\n");
  /* Skip heading in data file */
  fscanf(fpin, "%*[^\n] ");
  fscanf(fpin, "%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)))
    {
      fprintf(fpout, "Allocation failure\n");
      exit_status = -1;
      goto END;
    }

  /* Read A and B from data file, and copy A to AFP and B to X */

  fscanf(fpin, " %s%*[^\n] ", nag_enum_arg);
  /* nag_enum_name_to_value(x04nac).
   * Converts NAG enum member name to value
   */
  uplo = (Nag_UploType) nag_enum_name_to_value(nag_enum_arg);

  if (uplo == Nag_Upper)
    {
      for (i = 1; i <= n; ++i)
        {
          for (j = i; j <= n; ++j)
            fscanf(fpin, "%lf", &A_UPPER(i, j));
        }
      fscanf(fpin, "%*[^\n] ");
    }
  else
    {
      for (i = 1; i <= n; ++i)
        {
          for (j = 1; j <= i; ++j)
            fscanf(fpin, "%lf", &A_LOWER(i, j));
        }
      fscanf(fpin, "%*[^\n] ");
    }
  for (i = 1; i <= n; ++i)
    {
      for (j = 1; j <= nrhs; ++j)
        fscanf(fpin, "%lf", &B(i, j));
    }
  fscanf(fpin, "%*[^\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 */
  /* nag_dpptrf (f07gdc).
   * Cholesky factorization of real symmetric
   * positive-definite matrix, packed storage
   */
  nag_dpptrf(order, uplo, n, afp, &fail);
  if (fail.code != NE_NOERROR)
    {
      fprintf(fpout, "Error from nag_dpptrf (f07gdc).\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }
  /* Compute solution in the array X */
  /* nag_dpptrs (f07gec).
   * Solution of real symmetric positive-definite system of
   * linear equations, multiple right-hand sides, matrix
   * already factorized by nag_dpptrf (f07gdc), packed storage
   */
  nag_dpptrs(order, uplo, n, nrhs, afp, x, pdx, &fail);
  if (fail.code != NE_NOERROR)
    {
      fprintf(fpout, "Error from nag_dpptrs (f07gec).\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }
  /* Improve solution, and compute backward errors and */
  /* estimated bounds on the forward errors */
  /* nag_dpprfs (f07ghc).
   * Refined solution with error bounds of real symmetric
   * positive-definite system of linear equations, multiple
   * right-hand sides, packed storage
   */
  nag_dpprfs(order, uplo, n, nrhs, ap, afp, b, pdb, x, pdx, ferr, berr,
             &fail);
  if (fail.code != NE_NOERROR)
    {
      fprintf(fpout, "Error from nag_dpprfs (f07ghc).\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }
  /* Print solution */
  /* nag_gen_real_mat_print (x04cac).
   * Print real general matrix (easy-to-use)
   */
  if (outfile) fclose(fpout);
  nag_gen_real_mat_print(order, Nag_GeneralMatrix, Nag_NonUnitDiag, n, nrhs, x,
                         pdx, "Solution(s)", outfile, &fail);
  if (outfile && !(fpout = fopen(outfile, "a")))
    {
      exit_status = 2;
      goto END;
    }
  if (fail.code != NE_NOERROR)
    {
      fprintf(fpout, "Error from nag_gen_real_mat_print (x04cac).\n%s\n",
              fail.message);
      exit_status = 1;
      goto END;
    }
  fprintf(fpout, "\nBackward errors (machine-dependent)\n");
  for (j = 1; j <= nrhs; ++j)
    fprintf(fpout, "%11.1e%s", berr[j-1], j%7 == 0?"\n":" ");
  fprintf(fpout, "\nEstimated forward error bounds (machine-dependent)\n");
  for (j = 1; j <= nrhs; ++j)
    fprintf(fpout, "%11.1e%s", ferr[j-1], j%7 == 0?"\n":" ");
  fprintf(fpout, "\n");
 END:
  if (fpin != stdin) fclose(fpin);
  if (fpout != stdout) fclose(fpout);
  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;
}