SLAGS2  -  compute  2-by-2 orthogonal matrices U, V and Q,
       such that if ( UPPER ) then  U'*A*Q = U'*( A1 A2 )*Q = ( x
       0 ) ( 0 A3 ) ( x x ) and V'*B*Q = V'*( B1 B2 )*Q = ( x 0 )
       ( 0 B3 ) ( x x )  or if ( .NOT.UPPER ) then  U'*A*Q = U'*(
       A1  0 )*Q = ( x x ) ( A2 A3 ) ( 0 x ) and V'*B*Q = V'*( B1
       0 )*Q = ( x x ) ( B2 B3 ) ( 0 x )  The rows of the  trans
       formed A and B are parallel, where  U = ( CSU SNU ), V = (
       CSV SNV ), Q = ( CSQ SNQ ) ( -SNU CSU ) (  -SNV  CSV  )  (
       -SNQ CSQ )  Z' denotes the transpose of Z
SYNOPSIS
       SUBROUTINE SLAGS2( UPPER,  A1,  A2,  A3,  B1, B2, B3, CSU,
                          SNU, CSV, SNV, CSQ, SNQ )
           LOGICAL        UPPER
           REAL           A1, A2, A3, B1, B2, B3, CSQ, CSU,  CSV,
                          SNQ, SNU, SNV
PURPOSE
       SLAGS2  computes  2-by-2  orthogonal  matrices U, V and Q,
       such that if ( UPPER ) then U'*A*Q = U'*( A1 A2 )*Q = (  x
       0 ) ( 0 A3 ) ( x x ) and V'*B*Q = V'*( B1 B2 )*Q = ( x 0 )
       ( 0 B3 ) ( x x ) or if ( .NOT.UPPER ) then U'*A*Q  =  U'*(
       A1  0 )*Q = ( x x ) ( A2 A3 ) ( 0 x ) and V'*B*Q = V'*( B1
       0 )*Q = ( x x ) ( B2 B3 ) ( 0 x ) The rows of  the  trans
       formed  A and B are parallel, where U = ( CSU SNU ), V = (
       CSV SNV ), Q = ( CSQ SNQ ) ( -SNU CSU ) (  -SNV  CSV  )  (
       -SNQ CSQ ) Z' denotes the transpose of Z.
ARGUMENTS
       UPPER   (input) LOGICAL
               =  .TRUE.:  the  input  matrices A and B are upper
               triangular.
               = .FALSE.: the input matrices A and  B  are  lower
               triangular.
       A1      (input) REAL
               A2       (input)  REAL  A3       (input)  REAL  On
               entry, A1, A2 and A3 are  elements  of  the  input
               2-by-2 upper (lower) triangular matrix A.
       B1      (input) REAL
               B2       (input)  REAL  B3       (input)  REAL  On
               entry, B1, B2 and B3 are  elements  of  the  input
               2-by-2 upper (lower) triangular matrix B.
       CSU     (output) REAL
               SNU       (output)  REAL  The  desired  orthogonal
               matrix U.
               SNV      (output)  REAL  The  desired   orthogonal
               matrix V.
       CSQ     (output) REAL
               SNQ       (output)  REAL  The  desired  orthogonal
               matrix Q.
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