_ELMBAK(3F)							   _ELMBAK(3F)

NAME    [Toc]    [Back]

     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    [Toc]    [Back]

	  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    [Toc]    [Back]

     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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