SRC/claqr1.f(3)            Library Functions Manual            SRC/claqr1.f(3)

NAME
       SRC/claqr1.f

SYNOPSIS
   Functions/Subroutines
       subroutine claqr1 (n, h, ldh, s1, s2, v)
           CLAQR1 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 claqr1 (integer n, complex, dimension( ldh, * ) h, integer ldh,
       complex s1, complex s2, complex, dimension( * ) v)
       CLAQR1 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, CLAQR1 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 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

           S2

                     S2 is COMPLEX

                     S1 and S2 are the shifts defining K in (*) above.

           V

                     V is COMPLEX 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 claqr1.f.

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

LAPACK                          Version 3.12.0                 SRC/claqr1.f(3)