# include <complex.h>
# include <math.h>
# include <stdio.h>
# include <stdlib.h>

# include "eigs.h"

/******************************************************************************/

double complex *eigs ( int n, double *A )

/******************************************************************************/
/*
  Purpose:

    eigs() computes the eigenvalues of a real matrix in general storage.

  Discussion:

    The computation is done by calling the lapack() function dgeev()

  Licensing:

    This code is distributed under the MIT license. 

  Modified:

    06 June 2024

  Author:

    John Burkardt
*/
{
  int i;
  int info;
  char jobvl;
  char jobvr;
  double complex *lambda;
  int lda = n;
  int ldvl = 1;
  int ldvr = 1;
  int lwork;
  double *vl;
  double *vr;
  double *wi;
  double *work;
  double *wr;

  jobvl = 'N';
  jobvr = 'N';
  lda = n;
  wr = ( double * ) malloc ( n * sizeof ( double ) );
  wi = ( double * ) malloc ( n * sizeof ( double ) );
  vl = NULL;
  ldvl = 1;
  vr = NULL;
  ldvr = 1;
  work = ( double * ) malloc ( 3 * n * sizeof ( double ) );
  lwork = 3 * n;

  dgeev_ ( &jobvl, &jobvr, &n, A, &lda, wr, wi, vl, &ldvl, vr, &ldvr,
    work, &lwork, &info );

  lambda = ( double complex * ) malloc ( n * sizeof ( double complex ) );
  for ( i = 0; i < n; i++ )
  {
    lambda[i] = wr[i] + wi[i] * I;
  }

  free ( wi );
  free ( work );
  free ( wr );

  return lambda;
}