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/*
* dgeev.cpp
*
* Created on: 20 Apr 2011
* Author: auton
* ($Revision: 1 $)
*/
#include "dgeev.h"
void dgeev_sort(double *Er, double *Ei, int N)
{
double temp, *E2;
int i, j;
E2 = new double[N];
for (i=0; i<N; i++)
E2[i] = Er[i]*Er[i]+Ei[i]*Ei[i];
for (j=0; j<N; j++)
for (i=0; i<N-1; i++)
if (fabs(E2[i])<fabs(E2[i+1]))
{
temp = E2[i]; E2[i] = E2[i+1]; E2[i+1] = temp;
temp = Er[i]; Er[i] = Er[i+1]; Er[i+1] = temp;
temp = Ei[i]; Ei[i] = Ei[i+1]; Ei[i+1] = temp;
}
delete [] E2;
}
void dgeev_sort(double *Er, double *Ei, double **Evecs, int N)
{
double temp, *E2;
int i, j, k;
E2 = new double[N];
for (i=0; i<N; i++)
E2[i] = Er[i]*Er[i]+Ei[i]*Ei[i];
for (j=0; j<N; j++)
for (i=0; i<N-1; i++)
if (fabs(E2[i])<fabs(E2[i+1]))
{
temp = E2[i]; E2[i] = E2[i+1]; E2[i+1] = temp;
temp = Er[i]; Er[i] = Er[i+1]; Er[i+1] = temp;
temp = Ei[i]; Ei[i] = Ei[i+1]; Ei[i+1] = temp;
for (k=0; k<N; k++)
{
temp = Evecs[k][i];
Evecs[k][i] = Evecs[k][i+1];
Evecs[k][i+1] = temp;
}
}
delete [] E2;
}
double* dgeev_ctof(double **in, int rows, int cols)
{
double *out;
int i, j;
out = new double[rows*cols];
for (i=0; i<rows; i++)
for (j=0; j<cols; j++)
out[i+j*cols] = in[i][j];
return(out);
}
void dgeev_ftoc(double *in, double **out, int rows, int cols)
{
int i, j;
for (i=0; i<rows; i++)
for (j=0; j<cols; j++)
out[i][j] = in[i+j*cols];
}
void dgeev(double **H, int n, double *Er, double *Ei)
{
char jobvl, jobvr;
int lda, ldvl, ldvr, lwork, info;
double *a, *vl, *vr, *work;
jobvl = 'N'; // V/N to calculate/not calculate the left eigenvectors of the matrix H.
jobvr = 'N'; // As above, but for the right eigenvectors.
lda = n; // The leading dimension of the matrix a.
a = dgeev_ctof(H, n, lda); // Convert the matrix H from double pointer C form to single pointer Fortran form.
/* Whether we want them or not, we need to define the matrices
for the eigenvectors, and give their leading dimensions.
We also create a vector for work space. */
ldvl = n;
vl = new double[n*n];
ldvr = n;
vr = new double[n*n];
work = new double[4*n];
lwork = 4*n;
dgeev_(&jobvl, &jobvr, &n, a, &lda, Er, Ei, vl, &ldvl, vr, &ldvr, work, &lwork, &info);
dgeev_sort(Er, Ei, n); //Sort the results by eigenvalue in decreasing magnitude.
delete [] a;
delete [] vl;
delete [] vr;
delete [] work;
}
void dgeev(double **H, int n, double *Er, double *Ei, double **Evecs)
{
char jobvl, jobvr;
int lda, ldvl, ldvr, lwork, info;
double *a, *vl, *vr, *work;
jobvl = 'N';
jobvr = 'V';
lda = n;
a = dgeev_ctof(H, n, lda);
ldvl = n;
vl = new double[n*n];
ldvr = n;
vr = new double[n*n];
work = new double[4*n];
lwork = 4*n;
dgeev_(&jobvl, &jobvr, &n, a, &lda, Er, Ei, vl, &ldvl, vr, &ldvr, work, &lwork, &info);
dgeev_ftoc(vr, Evecs, n, ldvr);
dgeev_sort(Er, Ei, Evecs, n);
delete [] a;
delete [] vl;
delete [] vr;
delete [] work;
}
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