!>
!> CLAGS2 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.
!> 

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 REAL
!> 

A2

!>          A2 is COMPLEX
!> 

A3

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

B1

!>          B1 is REAL
!> 

B2

!>          B2 is COMPLEX
!> 

B3

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

CSU

!>          CSU is REAL
!> 

SNU

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

CSV

!>          CSV is REAL
!> 

SNV

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

CSQ

!>          CSQ is REAL
!> 

SNQ

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

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.