_TQLRAT(3F)							   _TQLRAT(3F)

NAME    [Toc]    [Back]

     TQLRAT, STQLRAT  -	 EISPACK routine.  This	subroutine finds the
     eigenvalues of a SYMMETRIC	TRIDIAGONAL matrix by the rational QL method.

SYNOPSYS    [Toc]    [Back]

	  subroutine  tqlrat(n,	d, e2, ierr)
	  integer	   n, ierr
	  double precision d(n), e2(n)

	  subroutine stqlrat(n,	d, e2, ierr)
	  integer	   n, ierr
	  real		   d(n), e2(n)

DESCRIPTION    [Toc]    [Back]

     On	Input

     N is the order of the matrix.

     D contains	the diagonal elements of the input matrix.

     E2	contains the squares of	the subdiagonal	elements of the	input matrix
     in	its last N-1 positions.	 E2(1) is arbitrary.  On Output

     D contains	the eigenvalues	in ascending order.  If	an error exit is made,
     the eigenvalues are correct and ordered for indices 1,2,...IERR-1,	but
     may not be	the smallest eigenvalues.

     E2	has been destroyed.

     IERR is set to Zero       for normal return, J	     if	the J-th
     eigenvalue	has not	been
	determined after 30 iterations.	 Calls PYTHAG(A,B) for sqrt(A**2 +
     B**2).  Questions and comments should be directed to B. S.	Garbow,
     APPLIED MATHEMATICS DIVISION, ARGONNE NATIONAL LABORATORY


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