/* nag_dgesv (f07aac) Example Program.
 *
 * Copyright 2008 Numerical Algorithms Group.
 *
 * Mark 23, 2011.
 */

#include <stdio.h>
#include <nag.h>
#include <nagx04.h>
#include <nag_stdlib.h>
#include <nagf07.h>

int main(void)
{
  /* Scalars */
  Integer       exit_status = 0, i, j, n, nrhs, pda, pdb;

  /* Arrays */
  double        *a = 0, *b = 0;
  Integer       *ipiv = 0;

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

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

  INIT_FAIL(fail);

  printf("nag_dgesv (f07aac) Example Program Results\n\n");

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

  scanf("%ld %ld%*[^\n]", &n, &nrhs);
  if (n < 0 || nrhs < 0)
    {
      printf("Invalid n or nrhs\n");
      exit_status = 1;
      return exit_status;
    }

  pda = n;
#ifdef NAG_COLUMN_MAJOR
  pdb = n;
#else
  pdb = nrhs;
#endif

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

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

  for (i = 1; i <= n; ++i)
    for (j = 1; j <= nrhs; ++j) scanf("%lf", &B(i, j));
  scanf("%*[^\n]");

  /* Solve the equations Ax = b for x using
   * nag_dgesv (f07aac)
   */
  nag_dgesv(order, n, nrhs, a, pda, ipiv, b, pdb, &fail);
  if (fail.code != NE_NOERROR)
    {
      printf("Error from nag_dgesv (f07aac).\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }

  /* Print solution */
  printf("Solution\n");
  for (i = 1; i <= n; ++i)
    for (j = 1; j <= nrhs; ++j)
      printf("%11.4f%s", B(i, j), j%7 == 0 || j == nrhs?"\n":" ");

  /* Print details of factorization using 
   * nag_gen_real_mat_print (x04cac)
   */
  printf("\n");
  fflush(stdout);
  nag_gen_real_mat_print(order, Nag_GeneralMatrix, Nag_NonUnitDiag, n, n, a,
                         pda, "Details of factorization", 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;
    }

  /* Print pivot indices */
  printf("\nPivot indices\n");
  for (i = 1; i <= n; ++i)
    printf("%11ld%s", ipiv[i-1], i%7 == 0 || i == n?"\n":" ");
 END:
  if (a) NAG_FREE(a);
  if (b) NAG_FREE(b);
  if (ipiv) NAG_FREE(ipiv);
  return exit_status;
}
#undef A
#undef B