/* nag_dspr2 (f16psc) Example Program.
 *
 * Copyright 2005 Numerical Algorithms Group.
 *
 * Mark 8, 2005.
 */

#include <stdio.h>
#include <nag.h>
#include <nag_stdlib.h>
#include <nagf16.h>
#include <nagx04.h>

int main(int argc, char *argv[])
{
  FILE          *fpin, *fpout;
  char          *outfile = 0;

  /* Scalars */
  double        alpha, beta;
  Integer       ap_len, exit_status, i, incx, incy, j, n, xlen, ylen;

  /* Arrays */
  double        *ap = 0, *x = 0, *y = 0;
  char          nag_enum_arg[40];

  /* Nag Types */
  NagError      fail;
  Nag_OrderType order;
  Nag_UploType  uplo;

#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]
  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]
  order = Nag_RowMajor;
#endif

  exit_status = 0;
  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_dspr2 (f16psc) Example Program Results\n\n");

  /* Skip heading in data file */
  fscanf(fpin, "%*[^\n] ");

  /* Read the problem dimension */
  fscanf(fpin, "%ld%*[^\n] ", &n);

  /* Read the uplo storage parameter */
  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);

  /* Read scalar parameters */
  fscanf(fpin, "%lf%lf%*[^\n] ", &alpha, &beta);
  /* Read increment parameter */
  fscanf(fpin, "%ld%ld%*[^\n] ", &incx, &incy);

  ap_len = n*(n+1)/2;
  xlen = MAX(1, 1 + (n - 1)*ABS(incx));
  ylen = MAX(1, 1 + (n - 1)*ABS(incy));

  if (n > 0)
    {
      /* Allocate memory */
      if (!(ap = NAG_ALLOC(ap_len, double)) ||
          !(x = NAG_ALLOC(xlen, double)) ||
          !(y = NAG_ALLOC(ylen, double)))
        {
          fprintf(fpout, "Allocation failure\n");
          exit_status = -1;
          goto END;
        }
    }
  else
    {
      fprintf(fpout, "Invalid n\n");
      exit_status = 1;
      return exit_status;
    }

  /* Input matrix A and vector x */

  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 = 0; i < xlen; ++i)
    fscanf(fpin, "%lf%*[^\n] ", &x[i]);
  for (i = 0; i < ylen; ++i)
    fscanf(fpin, "%lf%*[^\n] ", &y[i]);

  /* nag_dspr2(f16psc).
   * Rank two update of real symmetric matrix,
   * packed storage.
   */
  nag_dspr2(order, uplo, n, alpha, x, incx, y, incy, beta, ap, &fail);
  if (fail.code != NE_NOERROR)
    {
      fprintf(fpout, "Error from nag_dspr2.\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }

  /* Print updated matrix A */
  /* nag_pack_real_mat_print (x04ccc).
   * Print real packed triangular matrix (easy-to-use)
   */
  if (outfile) fclose(fpout);
  nag_pack_real_mat_print(order, uplo, Nag_NonUnitDiag, n, ap,
                          "Updated Matrix A", outfile, &fail);
  if (outfile && !(fpout = fopen(outfile, "a")))
    {
      exit_status = 2;
      goto END;
    }
  if (fail.code != NE_NOERROR)
    {
      fprintf(fpout, "Error from nag_pack_real_mat_print (x04ccc).\n%s\n",
              fail.message);
      exit_status = 1;
      goto END;
    }

 END:
  if (fpin != stdin) fclose(fpin);
  if (fpout != stdout) fclose(fpout);
  if (ap) NAG_FREE(ap);
  if (x) NAG_FREE(x);
  if (y) NAG_FREE(y);

  return exit_status;
}