SRC/zlags2.f(3)

NAME
SRC/zlags2.f

SYNOPSIS

  Functions/Subroutines
subroutine zlags2 (upper, a1, a2, a3, b1, b2, b3, csu, snu, csv, snv, csq, snq)
ZLAGS2

Function/Subroutine Documentation

  subroutine zlags2 (logical upper, double precision a1, complex*16 a2, double precision a3, double precision b1, complex*16 b2, double precision b3, double precision csu, complex*16 snu, double precision csv, complex*16 snv, double precision csq, complex*16 snq)

ZLAGS2

Purpose:

    !>
    !> ZLAGS2 computes 2-by-2 unitary matrices U, V and Q, such
    !> that if ( UPPER ) then
    !>
    !>           U**H *A*Q = U**H *( A1 A2 )*Q = ( x  0  )
    !>                             ( 0  A3 )     ( x  x  )
    !> and
    !>           V**H*B*Q = V**H *( B1 B2 )*Q = ( x  0  )
    !>                            ( 0  B3 )     ( x  x  )
    !>
    !> or if ( .NOT.UPPER ) then
    !>
    !>           U**H *A*Q = U**H *( A1 0  )*Q = ( x  x  )
    !>                             ( A2 A3 )     ( 0  x  )
    !> and
    !>           V**H *B*Q = V**H *( B1 0  )*Q = ( x  x  )
    !>                             ( B2 B3 )     ( 0  x  )
    !> where
    !>
    !>   U = (   CSU    SNU ), V = (  CSV    SNV ),
    !>       ( -SNU**H  CSU )      ( -SNV**H CSV )
    !>
    !>   Q = (   CSQ    SNQ )
    !>       ( -SNQ**H  CSQ )
    !>
    !> The rows of the transformed A and B are parallel. Moreover, if the
    !> input 2-by-2 matrix A is not zero, then the transformed (1,1) entry
    !> of A is not zero. If the input matrices A and B are both not zero,
    !> then the transformed (2,2) element of B is not zero, except when the
    !> first rows of input A and B are parallel and the second rows are
    !> zero.
    !>

Parameters
    UPPER

    !>          UPPER is LOGICAL
    !>          = .TRUE.: the input matrices A and B are upper triangular.
    !>          = .FALSE.: the input matrices A and B are lower triangular.
    !>

    A1

    !>          A1 is DOUBLE PRECISION
    !>

    A2

    !>          A2 is COMPLEX*16
    !>

    A3

    !>          A3 is DOUBLE PRECISION
    !>          On entry, A1, A2 and A3 are elements of the input 2-by-2
    !>          upper (lower) triangular matrix A.
    !>

    B1

    !>          B1 is DOUBLE PRECISION
    !>

    B2

    !>          B2 is COMPLEX*16
    !>

    B3

    !>          B3 is DOUBLE PRECISION
    !>          On entry, B1, B2 and B3 are elements of the input 2-by-2
    !>          upper (lower) triangular matrix B.
    !>

    CSU

    !>          CSU is DOUBLE PRECISION
    !>

    SNU

    !>          SNU is COMPLEX*16
    !>          The desired unitary matrix U.
    !>

    CSV

    !>          CSV is DOUBLE PRECISION
    !>

    SNV

    !>          SNV is COMPLEX*16
    !>          The desired unitary matrix V.
    !>

    CSQ

    !>          CSQ is DOUBLE PRECISION
    !>

    SNQ

    !>          SNQ is COMPLEX*16
    !>          The desired unitary matrix Q.
    !>

Author
    Univ. of Tennessee

    Univ. of California Berkeley

    Univ. of Colorado Denver

    NAG Ltd.

Definition at line 156 of file zlags2.f.

Author

Generated automatically by Doxygen for LAPACK from the source code.