SRC/zlaqr1.f(3)            Library Functions Manual            SRC/zlaqr1.f(3)

NAME
       SRC/zlaqr1.f

SYNOPSIS
   Functions/Subroutines
       subroutine zlaqr1 (n, h, ldh, s1, s2, v)
           ZLAQR1 sets a scalar multiple of the first column of the product of
           2-by-2 or 3-by-3 matrix H and specified shifts.

Function/Subroutine Documentation
   subroutine zlaqr1 (integer n, complex*16, dimension( ldh, * ) h, integer
       ldh, complex*16 s1, complex*16 s2, complex*16, dimension( * ) v)
       ZLAQR1 sets a scalar multiple of the first column of the product of
       2-by-2 or 3-by-3 matrix H and specified shifts.

       Purpose:


           !>
           !>      Given a 2-by-2 or 3-by-3 matrix H, ZLAQR1 sets v to a
           !>      scalar multiple of the first column of the product
           !>
           !>      (*)  K = (H - s1*I)*(H - s2*I)
           !>
           !>      scaling to avoid overflows and most underflows.
           !>
           !>      This is useful for starting double implicit shift bulges
           !>      in the QR algorithm.
           !>

       Parameters
           N

           !>          N is INTEGER
           !>              Order of the matrix H. N must be either 2 or 3.
           !>

           H

           !>          H is COMPLEX*16 array, dimension (LDH,N)
           !>              The 2-by-2 or 3-by-3 matrix H in (*).
           !>

           LDH

           !>          LDH is INTEGER
           !>              The leading dimension of H as declared in
           !>              the calling procedure.  LDH >= N
           !>

           S1

           !>          S1 is COMPLEX*16
           !>

           S2

           !>          S2 is COMPLEX*16
           !>
           !>          S1 and S2 are the shifts defining K in (*) above.
           !>

           V

           !>          V is COMPLEX*16 array, dimension (N)
           !>              A scalar multiple of the first column of the
           !>              matrix K in (*).
           !>

       Author
           Univ. of Tennessee


           Univ. of California Berkeley


           Univ. of Colorado Denver


           NAG Ltd.

       Contributors:
           Karen Braman and Ralph Byers, Department of Mathematics, University
           of Kansas, USA

       Definition at line 106 of file zlaqr1.f.

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

LAPACK                          Version 3.12.0                 SRC/zlaqr1.f(3)