RGG

[db]

The subroutine RGG, that computes eigenvalues and -vectors,
has me a bit confused, with respect to where the eigenvectors
are. It says

SUBROUTINE RGG(NM,N,A,B,ALFR,ALFI,BETA,MATZ,Z,IERR)
C
INTEGER N,NM,IERR,MATZ
DOUBLE PRECISION A(NM,N),B(NM,N),ALFR(N),ALFI(N),BETA(N),Z(NM,N)
LOGICAL TF
[...]

C ON OUTPUT

[...]

C Z CONTAINS THE REAL AND IMAGINARY PARTS OF THE EIGENVECTORS
C IF MATZ IS NOT ZERO. IF THE J-TH EIGENVALUE IS REAL, THE
C J-TH COLUMN OF Z CONTAINS ITS EIGENVECTOR. IF THE J-TH
C EIGENVALUE IS COMPLEX WITH POSITIVE IMAGINARY PART, THE
C J-TH AND (J+1)-TH COLUMNS OF Z CONTAIN THE REAL AND
C IMAGINARY PARTS OF ITS EIGENVECTOR. THE CONJUGATE OF THIS
C VECTOR IS THE EIGENVECTOR FOR THE CONJUGATE EIGENVALUE.

It seems to mean that Z has N columns and 2N rows, to accommodate both
real and imaginary vectors. But if the given Jth vector is at J and J+1,
wouldn't that overwrite the next vector, which would be at J+1 and J+2?

Where do I find the Jth complex eigenvector in Z?

--
Dieter Britz