SRC/dlaqz2.f(3)            Library Functions Manual            SRC/dlaqz2.f(3)

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

LAPACK                          Version 3.12.0                 SRC/dlaqz2.f(3)