/* nag_dspcon (f07pgc) Example Program.
 *
 * Copyright 2001 Numerical Algorithms Group.
 *
 * Mark 7, 2001.
 */

#include <stdio.h>
#include <nag.h>
#include <nag_stdlib.h>
#include <nagf07.h>
#include <nagf16.h>
#include <nagx02.h>

int main(void)
{
  /* Scalars */
  double        anorm, rcond;
  Integer       ap_len, i, j, n;
  Integer       exit_status = 0;
  NagError      fail;
  Nag_UploType  uplo;
  Nag_OrderType order;
  /* Arrays */
  Integer       *ipiv = 0;
  char          nag_enum_arg[40];
  double        *ap = 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]
  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

  INIT_FAIL(fail);

  printf("nag_dspcon (f07pgc) Example Program Results\n\n");
  /* Skip heading in data file */
  scanf("%*[^\n] ");
  scanf("%ld%*[^\n] ", &n);
  ap_len = n * (n + 1)/2;

  /* Allocate memory */
  if (!(ipiv = NAG_ALLOC(n, Integer)) ||
      !(ap = NAG_ALLOC(ap_len, double)))
    {
      printf("Allocation failure\n");
      exit_status = -1;
      goto END;
    }

  /* Read A from data file */
  scanf(" %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)
            scanf("%lf", &A_UPPER(i, j));
        }
      scanf("%*[^\n] ");
    }
  else
    {
      for (i = 1; i <= n; ++i)
        {
          for (j = 1; j <= i; ++j)
            scanf("%lf", &A_LOWER(i, j));
        }
      scanf("%*[^\n] ");
    }

  /* Compute norm of A */
  /* nag_dsp_norm (f16rdc).
   * 1-norm, infinity-norm, Frobenius norm, largest absolute
   * element, real symmetric matrix, packed storage
   */
  nag_dsp_norm(order, Nag_OneNorm, uplo, n, ap, &anorm, &fail);
  if (fail.code != NE_NOERROR)
    {
      printf("Error from nag_dsp_norm (f16rdc).\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }
  /* Factorize A */
  /* nag_dsptrf (f07pdc).
   * Bunch-Kaufman factorization of real symmetric indefinite
   * matrix, packed storage
   */
  nag_dsptrf(order, uplo, n, ap, ipiv, &fail);
  if (fail.code != NE_NOERROR)
    {
      printf("Error from nag_dsptrf (f07pdc).\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }
  /* Estimate condition number */
  /* nag_dspcon (f07pgc).
   * Estimate condition number of real symmetric indefinite
   * matrix, matrix already factorized by nag_dsptrf (f07pdc),
   * packed storage
   */
  nag_dspcon(order, uplo, n, ap, ipiv, anorm, &rcond, &fail);
  if (fail.code != NE_NOERROR)
    {
      printf("Error from nag_dspcon (f07pgc).\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }
  /* nag_machine_precision (x02ajc).
   * The machine precision
   */
  if (rcond >= nag_machine_precision)
    printf("Estimate of condition number =%11.2e\n\n", 1.0/rcond);
  else
    printf("A is singular to working precision\n");
 END:
  if (ipiv) NAG_FREE(ipiv);
  if (ap) NAG_FREE(ap);
  return exit_status;
}