/* nag_dggev (f08wac) Example Program.
 *
 * Copyright 2011 Numerical Algorithms Group.
 *
 * Mark 23, 2011.
 */

#include <math.h>
#include <stdio.h>
#include <nag.h>
#include <nag_stdlib.h>
#include <nagf08.h>
#include <nagx02.h>
#include <nagx04.h>
#include <naga02.h>

int main(void)
{
  /* Scalars */
  Complex           eig, eigl, eigr;
  double            sign, small;
  Integer           i, j, k, n, pda, pdb, pdvl, pdvr;
  Integer           exit_status = 0;

  /* Arrays */
  double            *a = 0, *alphai = 0, *alphar = 0, *b = 0, *beta = 0;
  double            *vl = 0, *vr = 0;
  char              nag_enum_arg[40];

  /* Nag Types */
  NagError          fail;
  Nag_OrderType     order;
  Nag_LeftVecsType  jobvl;
  Nag_RightVecsType jobvr;

#ifdef NAG_COLUMN_MAJOR
#define A(I, J)  a[(J-1)*pda + I - 1]
#define B(I, J)  b[(J-1)*pdb + I - 1]
#define VL(I, J) vl[(J-1)*pdvl + I - 1]
#define VR(I, J) vr[(J-1)*pdvr + 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]
#define VL(I, J) vl[(I-1)*pdvl + J - 1]
#define VR(I, J) vr[(I-1)*pdvr + J - 1]
  order = Nag_RowMajor;
#endif

  INIT_FAIL(fail);

  printf("nag_dggev (f08wac) Example Program Results\n");

  /* Skip heading in data file */
  scanf("%*[^\n]");
  scanf("%ld%*[^\n]", &n);
  if (n < 0)
    {
      printf("Invalid n\n");
      exit_status = 1;
      goto END;
    }
  scanf(" %s%*[^\n]", nag_enum_arg);
  /* nag_enum_name_to_value(x04nac).
   * Converts NAG enum member name to value
   */
  jobvl = (Nag_LeftVecsType) nag_enum_name_to_value(nag_enum_arg);
  scanf(" %s%*[^\n]", nag_enum_arg);
  jobvr = (Nag_RightVecsType) nag_enum_name_to_value(nag_enum_arg);
  pda = n;
  pdb = n;
  pdvl = (jobvl==Nag_LeftVecs?n:1);
  pdvr = (jobvr==Nag_RightVecs?n:1);

  /* Allocate memory */
  if (!(a      = NAG_ALLOC(n*n, double)) ||
      !(alphai = NAG_ALLOC(n, double)) ||
      !(alphar = NAG_ALLOC(n, double)) ||
      !(b      = NAG_ALLOC(n*n, double)) ||
      !(beta   = NAG_ALLOC(n, double)) ||
      !(vl     = NAG_ALLOC(pdvl*pdvl, double)) ||
      !(vr     = NAG_ALLOC(pdvr*pdvr, double)))
    {
      printf("Allocation failure\n");
      exit_status = -1;
      goto END;
    }

  /* Read in the matrices A and B */
  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 <= n; ++j) scanf("%lf", &B(i, j));
  scanf("%*[^\n]");

  /* Solve the generalized eigenvalue problem */
  nag_dggev(order, jobvl, jobvr, n, a, pda, b, pdb, alphar, alphai, beta, vl,
	    pdvl, vr, pdvr, &fail);
  if (fail.code != NE_NOERROR)
    {
      printf("Error from nag_dggev (f08wac).\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }

  small = nag_real_safe_small_number;
  for (j = 0; j < n; ++j)
    {
      printf("\n");
      if ((fabs(alphar[j]) + fabs(alphai[j])) * small >= fabs(beta[j]))
	{
	  printf("Eigenvalue %2ld is numerically infinite or "
		 "undetermined\n", j+1);
	  printf("alpha = (%13.4e, %13.4e), beta = %13.4e\n", alphar[j],
		 alphai[j], beta[j]);
	}
      else if (alphai[j] == 0.0)
	{
	  printf("Eigenvalue %2ld = %13.4e\n", j+1, alphar[j]/beta[j]);
	}
      else
	{
	  eig.re = alphar[j]/beta[j], eig.im = alphai[j]/beta[j];
	  printf("Eigenvalue %2ld = (%11.4e, %11.4e)\n", j+1, eig.re,
		 eig.im);
	}
      printf("\n");
      if (jobvl==Nag_LeftVecs) printf("%20s%8s", "Left Eigenvector", "");
      if (jobvr==Nag_RightVecs) printf("%20s", "Right Eigenvector");
      printf(" %2ld\n", j+1);
      if (alphai[j] == 0.0)
	for (i = 1; i <= n; ++i) {
	  if (jobvl==Nag_LeftVecs)
	    printf("%6s%11.4e%12s", "", VL(i, j+1)/VL(n, j+1), "");
	  if (jobvr==Nag_RightVecs)
	    printf("%6s%11.4e", "", VR(i, j+1)/VR(n, j+1));
	  printf("\n");
	}
      else 
	{
	  k = (alphai[j]>0.0?j+1:j);
          sign = (alphai[j]>0.0?1.0:-1.0);
	  if (jobvl==Nag_LeftVecs) eigl = nag_complex(VL(n,k), VL(n,k+1));
	  if (jobvr==Nag_RightVecs) eigr = nag_complex(VR(n,k), VR(n,k+1));
	  for (i = 1; i <= n; ++i)
	    {
	      if (jobvl==Nag_LeftVecs) {
		eig = nag_complex_divide(nag_complex(VL(i,k), VL(i,k+1)),
					 eigl);
		printf("(%11.4e,%11.4e) ", eig.re, sign*eig.im);
	      }
	      if (jobvr==Nag_RightVecs) {
		eig = nag_complex_divide(nag_complex(VR(i,k), VR(i,k+1)),
					 eigr);
		printf("(%11.4e,%11.4e)", eig.re, sign*eig.im);
	      }
	      printf("\n");
            }
	}
    }

 END:
  if (a)      NAG_FREE(a);
  if (alphai) NAG_FREE(alphai);
  if (alphar) NAG_FREE(alphar);
  if (b)      NAG_FREE(b);
  if (beta)   NAG_FREE(beta);
  if (vl)     NAG_FREE(vl);
  if (vr)     NAG_FREE(vr);

  return exit_status;
}