/* nag_det_real_sym (f03bfc) Example Program.
 *
 * Copyright 2011, Numerical Algorithms Group.
 *
 * Mark 23, 2011.
 */
#include <math.h>
#include <nag.h>
#include <nag_stdlib.h>
#include <nagf03.h>
#include <nagf07.h>
#include <nagx04.h>

int main(void)
{
  /* Scalars */
  Integer        exit_status = 0;
  Integer        i, id, j, n, pda;
  double         d;
  /* Arrays */
  char           nag_enum_arg[40];
  double         *a = 0;
  /* NAG types */
  NagError       fail;
  Nag_UploType   uplo;
  Nag_OrderType  order;
  Nag_MatrixType matrix;
  Nag_DiagType   diag = Nag_NonUnitDiag;

  printf("nag_det_real_sym (f03bfc) Example Program Results\n\n");

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

  scanf("%ld%*[^\n]", &n);
  pda = n;

  if (!(a = NAG_ALLOC(n*n, double)))
    {
      printf("Allocation failure\n");
      exit_status = -1;
      goto END;
    }

  /* Define matrix element A_ij in terms of elements of array a[k] */
#ifdef NAG_COLUMN_MAJOR
  order = Nag_ColMajor;
#define A(I, J) a[(J-1)*pda+(I-1)]
#else
  order = Nag_RowMajor;
#define A(J, I) a[(J-1)*pda+(I-1)]
#endif
  for (i = 1; i <= n; i++)
    for (j = 1; j <= n; j++)
      scanf("%lf", &A(i,j));
  scanf("%*[^\n] ");

  scanf("%s %*[^\n] ", nag_enum_arg);    /* Nag_Lower */
  uplo = (Nag_UploType) nag_enum_name_to_value(nag_enum_arg);
  if (uplo==Nag_Lower) {
    matrix = Nag_LowerMatrix;
  } else {
    matrix = Nag_UpperMatrix;
  }

  INIT_FAIL(fail);

  /* 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("%s\n", fail.message);
      exit_status = 1;
      goto END;
    }

  /* nag_gen_real_mat_print (x04cac)
   * Print real general matrix (easy-to-use)
   */
  fflush(stdout);
  nag_gen_real_mat_print(order, matrix, diag, n, n, a, pda,
                         "Array A after factorization", NULL, &fail);
  if (fail.code != NE_NOERROR)
    {
      printf("%s\n", fail.message);
      exit_status = 2;
      goto END;
    }

  /* nag_det_real_sym(f03bfc)
   * determinant of factorized real symmetric positive definite matrix
   */
  nag_det_real_sym(order, n, a, pda, &d, &id, &fail);
  if (fail.code != NE_NOERROR)
    {
      printf("%s\n", fail.message);
      exit_status = 3;
      goto END;
    }

  printf("\nd = %12.5f  id = %12" NAG_IFMT "\n", d, id);
  printf("Value of determinant = %12.5e\n", d*pow(2.0, id));

 END:
  if (a) NAG_FREE(a);

  return exit_status;
}