_ELMBAK(3F)_ELMBAK(3F)NAME
ELMBAK, SELMBAK - EISPACK routine. This subroutine forms the
eigenvectors of a REAL GENERAL matrix by back transforming those of the
corresponding upper Hessenberg matrix determined by ELMHES.
SYNOPSYS
subroutine elmbak(nm, low, igh, a, int, m, z)
integer nm, low, igh, m, int(igh)
double precision a(nm,igh), z(nm,m)
subroutine selmbak(nm, low, igh, a, int, m, z)
integer nm, low, igh, m, int(igh)
real a(nm,igh), z(nm,m)
DESCRIPTION
On INPUT
NM must be set to the row dimension of two-dimensional array parameters
as declared in the calling program dimension statement.
LOW and IGH are integers determined by the balancing subroutine BALANC.
If BALANC has not been used, set LOW=1 and IGH equal to the order of
the matrix.
A contains the multipliers which were used in the reduction by ELMHES
in its lower triangle below the subdiagonal.
INT contains information on the rows and columns interchanged in the
reduction by ELMHES. Only elements LOW through IGH are used.
M is the number of columns of Z to be back transformed.
Z contains the real and imaginary parts of the eigen- vectors to be back
transformed in its first M columns. On OUTPUT
Z contains the real and imaginary parts of the transformed eigenvectors
in its first M columns. Questions and comments should be directed to B.
S. Garbow, APPLIED MATHEMATICS DIVISION, ARGONNE NATIONAL LABORATORY
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