/* nag_dgesvx (f07abc) 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 */
  double                growth_factor, rcond;
  Integer               exit_status = 0, i, j, n, nrhs, pda, pdaf, pdb, pdx;

  /* Arrays */
  double                *a = 0, *af = 0, *b = 0, *berr = 0, *c = 0, *ferr = 0;
  double                *r = 0, *x = 0;
  Integer               *ipiv = 0;

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

#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_dgesvx (f07abc) 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;
  pdaf = n;
#ifdef NAG_COLUMN_MAJOR
  pdb = n;
  pdx = n;
#else
  pdb = nrhs;
  pdx = nrhs;
#endif

  /* Allocate memory */
  if (
    !(a  = NAG_ALLOC(n * n, double)) ||
    !(af = NAG_ALLOC(n * n, double)) ||
    !(b  = NAG_ALLOC(n * n, double)) ||
    !(berr = NAG_ALLOC(n, double)) ||
    !(c  = NAG_ALLOC(n, double)) ||
    !(ferr = NAG_ALLOC(n, double)) ||
    !(r  = NAG_ALLOC(n, double)) ||
    !(x  = NAG_ALLOC(n*n, 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_dgesvx (f07abc)
   */
  nag_dgesvx(order, Nag_EquilibrateAndFactor, Nag_NoTrans, n, nrhs, a, pda, af,
             pdaf, ipiv, &equed, r, c, b, pdb, x, pdx, &rcond, ferr, berr,
             &growth_factor, &fail);

  if (fail.code != NE_NOERROR && fail.code != NE_SINGULAR)
    {
      printf("Error from nag_dgesvx (f07abc).\n%s\n", fail.message);
      goto END;
      exit_status = 1;
    }

  /* Print solution using
   * nag_gen_real_mat_print (x04cac)
   */
  fflush(stdout);
  nag_gen_real_mat_print(order, Nag_GeneralMatrix, Nag_NonUnitDiag, n, nrhs, x,
                         pdx, "Solution(s)", 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 error bounds, condition number, the form of equilibration
   * and the pivot growth factor
   */
  printf("\nBackward errors (machine-dependent)\n");
  for (j = 1; j <= nrhs; ++j)
    printf("%11.1e%s", berr[j - 1], j%7 == 0 || j == nrhs?"\n":" ");
  printf("\n\nEstimated forward error bounds (machine-dependent)\n");

  for (j = 1; j <= nrhs; ++j)
    printf("%11.1e%s", ferr[j - 1], j%7 == 0 || j == nrhs?"\n":" ");
  printf("\n");

  if (equed == Nag_NoEquilibration)
    printf("A has not been equilibrated\n");
  else if (equed == Nag_RowEquilibration)
    printf("A has been row scaled as diag(R)*A\n");
  else if (equed == Nag_ColumnEquilibration)
    printf("A has been column scaled as A*diag(C)\n");
  else if (equed == Nag_RowAndColumnEquilibration)
    printf("A has been row and column scaled as diag(R)*A*diag(C)\n");

  printf("\nReciprocal condition number estimate of scaled matrix\n");
  printf("%11.1e\n\n", rcond);

  printf("Estimate of reciprocal pivot growth factor\n");
  printf("%11.1e\n", growth_factor);

  if (fail.code == NE_SINGULAR)
    {
      printf("Error from nag_dgesvx (f07abc).\n%s\n", fail.message);
      exit_status = 1;
    }

 END:
  if (a)  NAG_FREE(a);
  if (af) NAG_FREE(af);
  if (b)  NAG_FREE(b);
  if (berr) NAG_FREE(berr);
  if (c)  NAG_FREE(c);
  if (ferr) NAG_FREE(ferr);
  if (r)  NAG_FREE(r);
  if (x)  NAG_FREE(x);
  if (ipiv) NAG_FREE(ipiv);

  return exit_status;
}
#undef B
#undef A