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DLAGS2(3F)							    DLAGS2(3F)

NAME    [Toc]    [Back]

     DLAGS2 - 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    [Toc]    [Back]

     SUBROUTINE	DLAGS2(	UPPER, A1, A2, A3, B1, B2, B3, CSU, SNU, CSV, SNV,
			CSQ, SNQ )

	 LOGICAL	UPPER

	 DOUBLE		PRECISION A1, A2, A3, B1, B2, B3, CSQ, CSU, CSV, SNQ,
			SNU, SNV

PURPOSE    [Toc]    [Back]

     DLAGS2 computes 2-by-2 orthogonal matrices	U, V and Q, such that if (
     UPPER ) then

ARGUMENTS    [Toc]    [Back]

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

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

     CSU     (output) DOUBLE PRECISION
	     SNU     (output) DOUBLE PRECISION The desired orthogonal matrix
	     U.

     CSV     (output) DOUBLE PRECISION
	     SNV     (output) DOUBLE PRECISION The desired orthogonal matrix
	     V.

     CSQ     (output) DOUBLE PRECISION
	     SNQ     (output) DOUBLE PRECISION The desired orthogonal matrix
	     Q.
DLAGS2(3F)							    DLAGS2(3F)

NAME    [Toc]    [Back]

     DLAGS2 - 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    [Toc]    [Back]

     SUBROUTINE	DLAGS2(	UPPER, A1, A2, A3, B1, B2, B3, CSU, SNU, CSV, SNV,
			CSQ, SNQ )

	 LOGICAL	UPPER

	 DOUBLE		PRECISION A1, A2, A3, B1, B2, B3, CSQ, CSU, CSV, SNQ,
			SNU, SNV

PURPOSE    [Toc]    [Back]

     DLAGS2 computes 2-by-2 orthogonal matrices	U, V and Q, such that if (
     UPPER ) then

ARGUMENTS    [Toc]    [Back]

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

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

     CSU     (output) DOUBLE PRECISION
	     SNU     (output) DOUBLE PRECISION The desired orthogonal matrix
	     U.

     CSV     (output) DOUBLE PRECISION
	     SNV     (output) DOUBLE PRECISION The desired orthogonal matrix
	     V.

     CSQ     (output) DOUBLE PRECISION
	     SNQ     (output) DOUBLE PRECISION The desired orthogonal matrix
	     Q.


									PPPPaaaaggggeeee 1111
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