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)