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RedHat 9 (Linux i386) - man page for slasd9 (redhat section l)

SLASD9(l)					)					SLASD9(l)

NAME
       SLASD9 - find the square roots of the roots of the secular equation,

SYNOPSIS
       SUBROUTINE SLASD9( ICOMPQ, LDU, K, D, Z, VF, VL, DIFL, DIFR, DSIGMA, WORK, INFO )

	   INTEGER	  ICOMPQ, INFO, K, LDU

	   REAL 	  D( * ), DIFL( * ), DIFR( LDU, * ), DSIGMA( * ), VF( * ), VL( * ), WORK(
			  * ), Z( * )

PURPOSE
       SLASD9 finds the square roots of the roots of the secular equation, as defined by the val-
       ues in DSIGMA and Z.  It makes the
       appropriate  calls  to SLASD4, and stores, for each  element in D, the distance to its two
       nearest poles (elements in DSIGMA). It also updates the arrays VF and VL,  the  first  and
       last components of all the right singular vectors of the original bidiagonal matrix.

       SLASD9 is called from SLASD7.

ARGUMENTS
       ICOMPQ  (input) INTEGER
	       Specifies  whether  singular  vectors  are  to be computed in factored form in the
	       calling routine:

	       ICOMPQ = 0	      Compute singular values only.

	       ICOMPQ = 1	      Compute singular vector matrices in factored form also.	K
	       (input)	INTEGER  The  number  of  terms  in the rational function to be solved by
	       SLASD4.	K >= 1.

       D       (output) REAL array, dimension(K)
	       D(I) contains the updated singular values.

       DSIGMA  (input) REAL array, dimension(K)
	       The first K elements of this array contain the old roots of the deflated  updating
	       problem.  These are the poles of the secular equation.

       Z       (input) REAL array, dimension (K)
	       The  first  K  elements	of  this  array  contain the components of the deflation-
	       adjusted updating row vector.

       VF      (input/output) REAL array, dimension(K)
	       On entry, VF contains  information passed through SBEDE8.f On  exit,  VF  contains
	       the  first  K  components of the first components of all right singular vectors of
	       the bidiagonal matrix.

       VL      (input/output) REAL array, dimension(K)
	       On entry, VL contains  information passed through SBEDE8.f On  exit,  VL  contains
	       the first K components of the last components of all right singular vectors of the
	       bidiagonal matrix.

       DIFL    (output) REAL array, dimension (K).
	       On exit, DIFL(I) = D(I) - DSIGMA(I).

       DIFR    (output) REAL array,
	       dimension (LDU, 2) if ICOMPQ =1 and dimension (K) if ICOMPQ = 0.  On exit, DIFR(I,
	       1) = D(I) - DSIGMA(I+1), DIFR(K, 1) is not defined and will not be referenced.

	       If ICOMPQ = 1, DIFR(1:K, 2) is an array containing the normalizing factors for the
	       right singular vector matrix.

       WORK    (workspace) REAL array,
	       dimension at least (3 * K) Workspace.

       INFO    (output) INTEGER
	       = 0:  successful exit.
	       < 0:  if INFO = -i, the i-th argument had an illegal value.
	       > 0:  if INFO = 1, an singular value did not converge

FURTHER DETAILS
       Based on contributions by
	  Ming Gu and Huan Ren, Computer Science Division, University of
	  California at Berkeley, USA

LAPACK version 3.0			   15 June 2000 				SLASD9(l)


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