SRC/slaqz2.f(3)

NAME
SRC/slaqz2.f

SYNOPSIS

  Functions/Subroutines
subroutine slaqz2 (ilq, ilz, k, istartm, istopm, ihi, a, lda, b, ldb, nq, qstart, q, ldq, nz, zstart, z, ldz)
SLAQZ2

Function/Subroutine Documentation

  subroutine slaqz2 (logical, intent(in) ilq, logical, intent(in) ilz, integer, intent(in) k, integer, intent(in) istartm, integer, intent(in) istopm, integer, intent(in) ihi, real, dimension( lda, * ) a, integer, intent(in) lda, real, dimension( ldb, * ) b, integer, intent(in) ldb, integer, intent(in) nq, integer, intent(in) qstart, real, dimension( ldq, * ) q, integer, intent(in) ldq, integer, intent(in) nz, integer, intent(in) zstart, real, dimension( ldz, * ) z, integer, intent(in) ldz)

SLAQZ2

Purpose:

          SLAQZ2 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 REAL array, dimension (LDA,N)

    LDA

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

    B

              B is REAL 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 REAL 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 REAL 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 171 of file slaqz2.f.

Author

Generated automatically by Doxygen for LAPACK from the source code.