dladiv(l) [redhat man page]

DLADIV(l)								 )								 DLADIV(l)

NAME

       DLADIV - perform complex division in real arithmetic  a + i*b p + i*q = --------- c + i*d  The algorithm is due to Robert L

SYNOPSIS

       SUBROUTINE DLADIV( A, B, C, D, P, Q )

	   DOUBLE	  PRECISION A, B, C, D, P, Q

PURPOSE

       DLADIV  performs complex division in real arithmetic a + i*b p + i*q = --------- c + i*d The algorithm is due to Robert L. Smith and can be
       found in D. Knuth, The art of Computer Programming, Vol.2, p.195

ARGUMENTS

       A       (input) DOUBLE PRECISION
	       B       (input) DOUBLE PRECISION C	(input) DOUBLE PRECISION D	 (input) DOUBLE PRECISION The scalars a, b, c,	and  d	in
	       the above expression.

       P       (output) DOUBLE PRECISION
	       Q       (output) DOUBLE PRECISION The scalars p and q in the above expression.

LAPACK version 3.0						   15 June 2000 							 DLADIV(l)

DLAED5(l)								 )								 DLAED5(l)

NAME

       DLAED5  -  subroutine  computes the I-th eigenvalue of a symmetric rank-one modification of a 2-by-2 diagonal matrix  diag( D ) + RHO * Z *
       transpose(Z)

SYNOPSIS

       SUBROUTINE DLAED5( I, D, Z, DELTA, RHO, DLAM )

	   INTEGER	  I

	   DOUBLE	  PRECISION DLAM, RHO

	   DOUBLE	  PRECISION D( 2 ), DELTA( 2 ), Z( 2 )

PURPOSE

       This subroutine computes the I-th eigenvalue of a symmetric rank-one modification of a 2-by-2 diagonal matrix diag( D ) + RHO * Z *  trans-
       pose(Z) .  The diagonal elements in the array D are assumed to satisfy

		  D(i) < D(j)  for  i < j .

       We also assume RHO > 0 and that the Euclidean norm of the vector Z is one.

ARGUMENTS

       I      (input) INTEGER
	      The index of the eigenvalue to be computed.  I = 1 or I = 2.

       D      (input) DOUBLE PRECISION array, dimension (2)
	      The original eigenvalues.  We assume D(1) < D(2).

       Z      (input) DOUBLE PRECISION array, dimension (2)
	      The components of the updating vector.

       DELTA  (output) DOUBLE PRECISION array, dimension (2)
	      The vector DELTA contains the information necessary to construct the eigenvectors.

       RHO    (input) DOUBLE PRECISION
	      The scalar in the symmetric updating formula.

       DLAM   (output) DOUBLE PRECISION
	      The computed lambda_I, the I-th updated eigenvalue.

FURTHER DETAILS

       Based on contributions by
	  Ren-Cang Li, Computer Science Division, University of California
	  at Berkeley, USA

LAPACK version 3.0						   15 June 2000 							 DLAED5(l)