_HTRIBK(3F)							   _HTRIBK(3F)

NAME    [Toc]    [Back]

     HTRIBK, SHTRIBK  -	 EISPACK routine.  This	subroutine forms the
     eigenvectors of a COMPLEX HERMITIAN matrix	by back	transforming those of
     the corresponding real symmetric tridiagonal matrix determined by
     HTRIDI.

SYNOPSYS    [Toc]    [Back]

	  subroutine  htribk(nm, n, ar,	ai, tau, m, zr,	zi)
	  integer	   nm, n, m
	  double precision ar(nm,n),ai(nm,n),tau(2,n),zr(nm,m),zi(nm,m)

	  subroutine shtribk(nm, n, ar,	ai, tau, m, zr,	zi)
	  integer	   nm, n, m
	  real		   ar(nm,n),ai(nm,n),tau(2,n),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.

     N is the order of the matrix.

     AR	and AI contain information about the unitary trans- formations used in
     the reduction by  HTRIDI  in their	full lower triangles except for	the
     diagonal of AR.

     TAU contains further information about the	transformations.

     M is the number of	eigenvectors to	be back	transformed.

     ZR	contains the eigenvectors to be	back transformed in its	first M
     columns.  On OUTPUT

     ZR	and ZI contain the real	and imaginary parts, respectively, of the
     transformed eigenvectors in their first M columns.	 Note that the last
     component of each returned	vector is real and that	vector Euclidean norms
     are preserved.  Questions and comments should be directed to B. S.
     Garbow, APPLIED MATHEMATICS DIVISION, ARGONNE NATIONAL LABORATORY


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