_RT(3F)								       _RT(3F)

NAME    [Toc]    [Back]

     RT, SRT -	EISPACK	routine.  This subroutine calls	the recommended
     sequence of subroutines from the eigensystem subroutine package (EISPACK)
     to	find the eigenvalues and eigenvectors (if desired) of a	special	REAL
     TRIDIAGONAL matrix.

SYNOPSYS    [Toc]    [Back]

	  subroutine  rt(nm, n,	a, w, matz, z, fv1, ierr)
	  integer	   nm, n, matz,	ierr
	  double precision a(nm,3), w(n), z(nm n), fv1(n)

	  subroutine srt(nm, n,	a, w, matz, z, fv1, ierr)
	  integer	   nm, n, matz,	ierr
	  real		   a(nm,3), w(n), z(nm n), fv1(n)

DESCRIPTION    [Toc]    [Back]

     On	Input

     NM	must be	set to the row dimension of the	two-dimensional	array
     parameters	as declared in the calling program dimension statement.

     N is the order of the matrix  A.

     A contains	the special real tridiagonal matrix in its first three
     columns.  The subdiagonal elements	are stored in the last	N-1  positions
     of	the first column, the diagonal elements	in the second column, and the
     superdiagonal elements in the first  N-1  positions of the	third column.
     elements  A(1,1)  and  A(N,3)  are	arbitrary.

     MATZ is an	integer	variable set equal to zero if only eigenvalues are
     desired.  Otherwise it is set to any non-zero integer for both
     eigenvalues and eigenvectors.  On Output

     W contains	the eigenvalues	in ascending order.

     Z contains	the eigenvectors if MATZ is not	zero.

     IERR is an	integer	output variable	set equal to an	error completion code
     described in section 2B of	the documentation.  The	normal completion code
     is	zero.

     FV1 is a temporary	storage	array. Questions and comments should be
     directed to B. S. Garbow, APPLIED MATHEMATICS DIVISION, ARGONNE NATIONAL
     LABORATORY


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