/* nag_dpocon (f07fgc) Example Program.
 *
 * Copyright 2001 Numerical Algorithms Group.
 *
 * Mark 7, 2001.
 */

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

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

#ifdef NAG_COLUMN_MAJOR
#define A(I, J) a[(J-1)*pda + I - 1]
  order = Nag_ColMajor;
#else
#define A(I, J) a[(I-1)*pda + J - 1]
  order = Nag_RowMajor;
#endif

  INIT_FAIL(fail);

  printf("nag_dpocon (f07fgc) Example Program Results\n\n");

  /* Skip heading in data file */
  scanf("%*[^\n] ");
  scanf("%ld%*[^\n] ", &n);
#ifdef NAG_COLUMN_MAJOR
  pda = n;
#else
  pda = n;
#endif

  /* Allocate memory */
  if (!(a = NAG_ALLOC(n * n, 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(i, j));
        }
      scanf("%*[^\n] ");
    }
  else
    {
      for (i = 1; i <= n; ++i)
        {
          for (j = 1; j <= i; ++j)
            scanf("%lf", &A(i, j));
        }
      scanf("%*[^\n] ");
    }
  /* Compute norm of A */
  /* nag_dsy_norm (f16rcc).
   * 1-norm, infinity-norm, Frobenius norm, largest absolute
   * element, real symmetric matrix
   */
  nag_dsy_norm(order, Nag_OneNorm, uplo, n, a, pda, &anorm, &fail);
  if (fail.code != NE_NOERROR)
    {
      printf("Error from nag_dsy_norm (f16rcc).\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }
  /* Factorize A */
  /* nag_dpotrf (f07fdc).
   * Cholesky factorization of real symmetric
   * positive-definite matrix
   */
  nag_dpotrf(order, uplo, n, a, pda, &fail);
  if (fail.code != NE_NOERROR)
    {
      printf("Error from nag_dpotrf (f07fdc).\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }
  /* Estimate condition number */
  /* nag_dpocon (f07fgc).
   * Estimate condition number of real symmetric
   * positive-definite matrix, matrix already factorized by
   * nag_dpotrf (f07fdc)
   */
  nag_dpocon(order, uplo, n, a, pda, anorm, &rcond, &fail);
  if (fail.code != NE_NOERROR)
    {
      printf("Error from nag_dpocon (f07fgc).\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 (a) NAG_FREE(a);
  return exit_status;
}