/* nag_dpotri (f07fjc) 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(void)
{
  /* Scalars */
  Integer        i, j, n, pda;
  Integer        exit_status = 0;
  Nag_UploType   uplo;
  Nag_MatrixType matrix;
  NagError       fail;
  Nag_OrderType  order;
  /* Arrays */
  char           nag_enum_arg[40];
  double         *a = 0;

#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_dpotri (f07fjc) 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)
    {
      matrix = Nag_UpperMatrix;
      for (i = 1; i <= n; ++i)
        {
          for (j = i; j <= n; ++j)
            scanf("%lf", &A(i, j));
        }
      scanf("%*[^\n] ");
    }
  else
    {
      matrix = Nag_LowerMatrix;
      for (i = 1; i <= n; ++i)
        {
          for (j = 1; j <= i; ++j)
            scanf("%lf", &A(i, j));
        }
      scanf("%*[^\n] ");
    }

  /* 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;
    }
  /* Compute inverse of A */
  /* nag_dpotri (f07fjc).
   * Inverse of real symmetric positive-definite matrix,
   * matrix already factorized by nag_dpotrf (f07fdc)
   */
  nag_dpotri(order, uplo, n, a, pda, &fail);
  if (fail.code != NE_NOERROR)
    {
      printf("Error from nag_dpotri (f07fjc).\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }
  /* Print inverse */
  /* nag_gen_real_mat_print (x04cac).
   * Print real general matrix (easy-to-use)
   */
  fflush(stdout);
  nag_gen_real_mat_print(order, matrix, Nag_NonUnitDiag, n, n, a, pda,
                         "Inverse", 0, &fail);
  if (fail.code != NE_NOERROR)
    {
      printf("Error from nag_gen_real_mat_print (x04cac).\n%s\n",
              fail.message);
      exit_status = 1;
      goto END;
    }

 END:
  if (a) NAG_FREE(a);

  return exit_status;
}