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dlasd5.f(3) [debian man page]

dlasd5.f(3)							      LAPACK							       dlasd5.f(3)

NAME

       dlasd5.f -

SYNOPSIS

   Functions/Subroutines
       subroutine dlasd5 (I, D, Z, DELTA, RHO, DSIGMA, WORK)
	   DLASD5

Function/Subroutine Documentation
   subroutine dlasd5 (integerI, double precision, dimension( 2 )D, double precision, dimension( 2 )Z, double precision, dimension( 2 )DELTA,
       double precisionRHO, double precisionDSIGMA, double precision, dimension( 2 )WORK)
       DLASD5

       Purpose:

	    This subroutine computes the square root of the I-th eigenvalue
	    of a positive symmetric rank-one modification of a 2-by-2 diagonal
	    matrix

		       diag( D ) * diag( D ) +	RHO * Z * transpose(Z) .

	    The diagonal entries in the array D are assumed to satisfy

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

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

       Parameters:
	   I

		     I is INTEGER
		    The index of the eigenvalue to be computed.  I = 1 or I = 2.

	   D

		     D is DOUBLE PRECISION array, dimension ( 2 )
		    The original eigenvalues.  We assume 0 <= D(1) < D(2).

	   Z

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

	   DELTA

		     DELTA is DOUBLE PRECISION array, dimension ( 2 )
		    Contains (D(j) - sigma_I) in its  j-th component.
		    The vector DELTA contains the information necessary
		    to construct the eigenvectors.

	   RHO

		     RHO is DOUBLE PRECISION
		    The scalar in the symmetric updating formula.

	   DSIGMA

		     DSIGMA is DOUBLE PRECISION
		    The computed sigma_I, the I-th updated eigenvalue.

	   WORK

		     WORK is DOUBLE PRECISION array, dimension ( 2 )
		    WORK contains (D(j) + sigma_I) in its  j-th component.

       Author:
	   Univ. of Tennessee

	   Univ. of California Berkeley

	   Univ. of Colorado Denver

	   NAG Ltd.

       Date:
	   November 2011

       Contributors:
	   Ren-Cang Li, Computer Science Division, University of California at Berkeley, USA

       Definition at line 117 of file dlasd5.f.

Author
       Generated automatically by Doxygen for LAPACK from the source code.

Version 3.4.1							  Sun May 26 2013						       dlasd5.f(3)

Check Out this Related Man Page

DLASD5(l)								 )								 DLASD5(l)

NAME

       DLASD5  -  subroutine  computes	the  square root of the I-th eigenvalue of a positive symmetric rank-one modification of a 2-by-2 diagonal
       matrix  diag( D ) * diag( D ) + RHO * Z * transpose(Z)

SYNOPSIS

       SUBROUTINE DLASD5( I, D, Z, DELTA, RHO, DSIGMA, WORK )

	   INTEGER	  I

	   DOUBLE	  PRECISION DSIGMA, RHO

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

PURPOSE

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

		  0 <= 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 0 <= D(1) < D(2).

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

       DELTA  (output) DOUBLE PRECISION array, dimension ( 2 )
	      Contains	(D(j)  - lambda_I) in its  j-th component.  The vector DELTA contains the information necessary to construct the eigenvec-
	      tors.

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

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

       WORK   (workspace) DOUBLE PRECISION array, dimension ( 2 )
	      WORK contains (D(j) + sigma_I) in its  j-th component.

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 							 DLASD5(l)
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