SRC/dlaqz1.f(3)

NAME
SRC/dlaqz1.f

SYNOPSIS

  Functions/Subroutines
subroutine dlaqz1 (a, lda, b, ldb, sr1, sr2, si, beta1, beta2, v)
DLAQZ1

Function/Subroutine Documentation

  subroutine dlaqz1 (double precision, dimension( lda, * ), intent(in) a, integer, intent(in) lda, double precision, dimension( ldb, * ), intent(in) b, integer, intent(in) ldb, double precision, intent(in) sr1, double precision, intent(in) sr2, double precision, intent(in) si, double precision, intent(in) beta1, double precision, intent(in) beta2, double precision, dimension( * ), intent(out) v)

DLAQZ1

Purpose:

    !>
    !>      Given a 3-by-3 matrix pencil (A,B), DLAQZ1 sets v to a
    !>      scalar multiple of the first column of the product
    !>
    !>      (*)  K = (A - (beta2*sr2 - i*si)*B)*B^(-1)*(beta1*A - (sr2 + i*si2)*B)*B^(-1).
    !>
    !>      It is assumed that either
    !>
    !>              1) sr1 = sr2
    !>          or
    !>              2) si = 0.
    !>
    !>      This is useful for starting double implicit shift bulges
    !>      in the QZ algorithm.
    !>

Parameters
    A

    !>          A is DOUBLE PRECISION array, dimension (LDA,N)
    !>              The 3-by-3 matrix A in (*).
    !>

    LDA

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

    B

    !>          B is DOUBLE PRECISION array, dimension (LDB,N)
    !>              The 3-by-3 matrix B in (*).
    !>

    LDB

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

    SR1

    !>          SR1 is DOUBLE PRECISION
    !>

    SR2

    !>          SR2 is DOUBLE PRECISION
    !>

    SI

    !>          SI is DOUBLE PRECISION
    !>

    BETA1

    !>          BETA1 is DOUBLE PRECISION
    !>

    BETA2

    !>          BETA2 is DOUBLE PRECISION
    !>

    V

    !>          V is DOUBLE PRECISION array, dimension (N)
    !>              A scalar multiple of the first column of the
    !>              matrix K in (*).
    !>

Author
    Thijs Steel, KU Leuven

Date
    May 2020

Definition at line 125 of file dlaqz1.f.

Author

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