/* nag_lapacklin_dsgesv (f07acc) Example Program.
 *
 * Copyright 2024 Numerical Algorithms Group.
 *
 * Mark 30.3, 2024.
 */

#include <math.h>
#include <nag.h>
#include <stdio.h>

int main(void) {

  /* Scalars */
  Integer exit_status = 0;
  Integer i, iter, j, n, nrhs, pda, pdb, pdx;

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

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

  INIT_FAIL(fail);

  printf("nag_lapacklin_dsgesv (f07acc) Example Program Results\n\n");
  /* Skip heading in data file */
  scanf("%*[^\n]");
  scanf("%" NAG_IFMT "%" NAG_IFMT "%*[^\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;
  pdx = n;
#define A(I, J) a[(J - 1) * pda + I - 1]
#define B(I, J) b[(J - 1) * pdb + I - 1]
  order = Nag_ColMajor;
#else
  pdb = nrhs;
  pdx = nrhs;
#define A(I, J) a[(I - 1) * pda + J - 1]
#define B(I, J) b[(I - 1) * pdb + J - 1]
  order = Nag_RowMajor;
#endif

  /* Allocate memory */
  if (!(a = NAG_ALLOC(n * n, double)) || !(b = NAG_ALLOC(n * nrhs, double)) ||
      !(x = 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_lapacklin_dsgesv (f07acc)
   * Mixed precision real system solver.
   */
  nag_lapacklin_dsgesv(order, n, nrhs, a, pda, ipiv, b, pdb, x, pdx, &iter,
                       &fail);
  if (fail.code != NE_NOERROR) {
    printf("Error from nag_lapacklin_dsgesv (f07acc).\n%s\n", fail.message);
    exit_status = 1;
    goto END;
  }

  /* Print solution using
   * nag_file_print_matrix_real_gen (x04cac)
   */
  fflush(stdout);
  nag_file_print_matrix_real_gen(order, Nag_GeneralMatrix, Nag_NonUnitDiag, n,
                                 nrhs, x, pdx, "Solution(s)", 0, &fail);
  if (fail.code != NE_NOERROR) {
    printf("Error from nag_file_print_matrix_real_gen (x04cac).\n%s\n",
           fail.message);
    exit_status = 1;
    goto END;
  }

  /* Print pivot indices */
  printf("\nPivot indices\n");
  for (i = 0; i < n; i++)
    printf("%11" NAG_IFMT "%s", ipiv[i], (i + 1) % 7 ? " " : "\n");
  printf("\n");

END:
  NAG_FREE(a);
  NAG_FREE(b);
  NAG_FREE(x);
  NAG_FREE(ipiv);

  return exit_status;
}

#undef A
#undef B