_CORTB(3F)							    _CORTB(3F)

NAME    [Toc]    [Back]

     CORTB, SCORTB   -	EISPACK	routine.  This subroutine forms	the
     eigenvectors of a COMPLEX GENERAL matrix by back transforming those of
     the corresponding upper Hessenberg	matrix determined by  CORTH.

SYNOPSYS    [Toc]    [Back]

	  subroutine  cortb(nm,	low, igh, ar, ai, ortr,	orti, m, zr, zi)
	  integer	   nm, low, igh, m
	  double precision ar(nm,igh), ai(nm,igh), ortr(igh), orti(igh)
	  double precision zr(nm,m),   zi(nm,m)

	  subroutine scortb(nm,	low, igh, ar, ai, ortr,	orti, m, zr, zi)
	  integer	   nm, low, igh, m
	  real		   ar(nm,igh), ai(nm,igh), ortr(igh), orti(igh)
	  real		   zr(nm,m),   zi(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  CBAL.
     If	 CBAL  has not been used, set LOW=1 and	IGH equal to the order of the
     matrix.

     AR	and AI contain information about the unitary transformations used in
     the reduction by  CORTH in	their strict lower triangles.

     ORTR and ORTI contain further information about the transformations used
     in	the reduction by  CORTH.  Only elements	LOW through IGH	are used.

     M is the number of	columns	of ZR and ZI to	be back	transformed.

     ZR	and ZI contain the real	and imaginary parts, respectively, of the
     eigenvectors to be	back transformed in their first	M columns.  On OUTPUT

     ZR	and ZI contain the real	and imaginary parts, respectively, of the
     transformed eigenvectors in their first M columns.

     ORTR and ORTI have	been altered. Note that	CORTB preserves	vector
     Euclidean norms.  Questions and comments should be	directed to B. S.
     Garbow, APPLIED MATHEMATICS DIVISION, ARGONNE NATIONAL LABORATORY


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