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/home/abuild/rpmbuild/BUILD/lapack-3.12.0/SRC/dlaqz2.f(3) Library Functions Manual /home/abuild/rpmbuild/BUILD/lapack-3.12.0/SRC/dlaqz2.f(3)

NAME

/home/abuild/rpmbuild/BUILD/lapack-3.12.0/SRC/dlaqz2.f

SYNOPSIS

Functions/Subroutines


subroutine DLAQZ2 (ilq, ilz, k, istartm, istopm, ihi, a, lda, b, ldb, nq, qstart, q, ldq, nz, zstart, z, ldz)
DLAQZ2

Function/Subroutine Documentation

subroutine DLAQZ2 (logical, intent(in) ilq, logical, intent(in) ilz, integer, intent(in) k, integer, intent(in) istartm, integer, intent(in) istopm, integer, intent(in) ihi, double precision, dimension( lda, * ) a, integer, intent(in) lda, double precision, dimension( ldb, * ) b, integer, intent(in) ldb, integer, intent(in) nq, integer, intent(in) qstart, double precision, dimension( ldq, * ) q, integer, intent(in) ldq, integer, intent(in) nz, integer, intent(in) zstart, double precision, dimension( ldz, * ) z, integer, intent(in) ldz)

DLAQZ2

Purpose:

!>
!>      DLAQZ2 chases a 2x2 shift bulge in a matrix pencil down a single position
!>

Parameters

ILQ 

!>          ILQ is LOGICAL
!>              Determines whether or not to update the matrix Q
!>

ILZ

!>          ILZ is LOGICAL
!>              Determines whether or not to update the matrix Z
!>

K

!>          K is INTEGER
!>              Index indicating the position of the bulge.
!>              On entry, the bulge is located in
!>              (A(k+1:k+2,k:k+1),B(k+1:k+2,k:k+1)).
!>              On exit, the bulge is located in
!>              (A(k+2:k+3,k+1:k+2),B(k+2:k+3,k+1:k+2)).
!>

ISTARTM

!>          ISTARTM is INTEGER
!>

ISTOPM

!>          ISTOPM is INTEGER
!>              Updates to (A,B) are restricted to
!>              (istartm:k+3,k:istopm). It is assumed
!>              without checking that istartm <= k+1 and
!>              k+2 <= istopm
!>

IHI

!>          IHI is INTEGER
!>

A

!>          A is DOUBLE PRECISION array, dimension (LDA,N)
!>

LDA

!>          LDA is INTEGER
!>              The leading dimension of A as declared in
!>              the calling procedure.
!>

B

!>          B is DOUBLE PRECISION array, dimension (LDB,N)
!>

LDB

!>          LDB is INTEGER
!>              The leading dimension of B as declared in
!>              the calling procedure.
!>

NQ

!>          NQ is INTEGER
!>              The order of the matrix Q
!>

QSTART

!>          QSTART is INTEGER
!>              Start index of the matrix Q. Rotations are applied
!>              To columns k+2-qStart:k+4-qStart of Q.
!>

Q

!>          Q is DOUBLE PRECISION array, dimension (LDQ,NQ)
!>

LDQ

!>          LDQ is INTEGER
!>              The leading dimension of Q as declared in
!>              the calling procedure.
!>

NZ

!>          NZ is INTEGER
!>              The order of the matrix Z
!>

ZSTART

!>          ZSTART is INTEGER
!>              Start index of the matrix Z. Rotations are applied
!>              To columns k+1-qStart:k+3-qStart of Z.
!>

Z

!>          Z is DOUBLE PRECISION array, dimension (LDZ,NZ)
!>

LDZ

!>          LDZ is INTEGER
!>              The leading dimension of Q as declared in
!>              the calling procedure.
!>

Author

Thijs Steel, KU Leuven

Date

May 2020

Definition at line 172 of file dlaqz2.f.

Author

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Version 3.12.0 LAPACK