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slags2

 NAME
      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 transformed 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

 ARGUMENTS
      UPPER   (input) LOGICAL
              = .TRUE.: the input matrices A and B are upper tri-
              angular.
              = .FALSE.: the input matrices A and B are lower tri-
              angular.

      A1      (input) REAL
              A2      (input) REAL A3      (input) REAL On entry,
              A1, A2 and A3 are entries 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 entries of the input 2-by-2 upper
              (lower) triangular matrix B.

      CSU     (output) REAL
              SNU     (output) REAL The desired orthogonal matrix
              U.

      CSV     (output) REAL
              SNV     (output) REAL The desired orthogonal matrix
              V.

      CSQ     (output) REAL

              SNQ     (output) REAL The desired orthogonal matrix
              Q.