SUBROUTINE CLAGS2( UPPER, A1, A2, A3, B1, B2, B3, CSU, SNU, CSV,
$ SNV, CSQ, SNQ )
LOGICAL UPPER
REAL A1, A3, B1, B3, CSQ, CSU, CSV
COMPLEX A2, B2, SNQ, SNU, SNV
REAL ZERO, ONE
PARAMETER ( ZERO = 0.0E+0, ONE = 1.0E+0 )
REAL A, AUA11, AUA12, AUA21, AUA22, AVB11, AVB12,
$ AVB21, AVB22, CSL, CSR, D, FB, FC, S1, S2, SNL,
$ SNR, UA11R, UA22R, VB11R, VB22R
COMPLEX B, C, D1, R, T, UA11, UA12, UA21, UA22, VB11,
$ VB12, VB21, VB22
EXTERNAL CLARTG, SLASV2
INTRINSIC ABS, AIMAG, CMPLX, CONJG, REAL
REAL ABS1
ABS1( T ) = ABS( REAL( T ) ) + ABS( AIMAG( T ) )
IF( UPPER ) THEN
A = A1*B3
D = A3*B1
B = A2*B1 - A1*B2
FB = ABS( B )
D1 = ONE
IF( FB.NE.ZERO )
$ D1 = B / FB
CALL SLASV2( A, FB, D, S1, S2, SNR, CSR, SNL, CSL )
IF( ABS( CSL ).GE.ABS( SNL ) .OR. ABS( CSR ).GE.ABS( SNR ) )
$ THEN
UA11R = CSL*A1
UA12 = CSL*A2 + D1*SNL*A3
VB11R = CSR*B1
VB12 = CSR*B2 + D1*SNR*B3
AUA12 = ABS( CSL )*ABS1( A2 ) + ABS( SNL )*ABS( A3 )
AVB12 = ABS( CSR )*ABS1( B2 ) + ABS( SNR )*ABS( B3 )
IF( ( ABS( UA11R )+ABS1( UA12 ) ).EQ.ZERO ) THEN
CALL CLARTG( -CMPLX( VB11R ), CONJG( VB12 ), CSQ, SNQ,
$ R )
ELSE IF( ( ABS( VB11R )+ABS1( VB12 ) ).EQ.ZERO ) THEN
CALL CLARTG( -CMPLX( UA11R ), CONJG( UA12 ), CSQ, SNQ,
$ R )
ELSE IF( AUA12 / ( ABS( UA11R )+ABS1( UA12 ) ).LE.AVB12 /
$ ( ABS( VB11R )+ABS1( VB12 ) ) ) THEN
CALL CLARTG( -CMPLX( UA11R ), CONJG( UA12 ), CSQ, SNQ,
$ R )
ELSE
CALL CLARTG( -CMPLX( VB11R ), CONJG( VB12 ), CSQ, SNQ,
$ R )
END IF
CSU = CSL
SNU = -D1*SNL
CSV = CSR
SNV = -D1*SNR
ELSE
UA21 = -CONJG( D1 )*SNL*A1
UA22 = -CONJG( D1 )*SNL*A2 + CSL*A3
VB21 = -CONJG( D1 )*SNR*B1
VB22 = -CONJG( D1 )*SNR*B2 + CSR*B3
AUA22 = ABS( SNL )*ABS1( A2 ) + ABS( CSL )*ABS( A3 )
AVB22 = ABS( SNR )*ABS1( B2 ) + ABS( CSR )*ABS( B3 )
IF( ( ABS1( UA21 )+ABS1( UA22 ) ).EQ.ZERO ) THEN
CALL CLARTG( -CONJG( VB21 ), CONJG( VB22 ), CSQ, SNQ, R )
ELSE IF( ( ABS1( VB21 )+ABS( VB22 ) ).EQ.ZERO ) THEN
CALL CLARTG( -CONJG( UA21 ), CONJG( UA22 ), CSQ, SNQ, R )
ELSE IF( AUA22 / ( ABS1( UA21 )+ABS1( UA22 ) ).LE.AVB22 /
$ ( ABS1( VB21 )+ABS1( VB22 ) ) ) THEN
CALL CLARTG( -CONJG( UA21 ), CONJG( UA22 ), CSQ, SNQ, R )
ELSE
CALL CLARTG( -CONJG( VB21 ), CONJG( VB22 ), CSQ, SNQ, R )
END IF
CSU = SNL
SNU = D1*CSL
CSV = SNR
SNV = D1*CSR
END IF
ELSE
A = A1*B3
D = A3*B1
C = A2*B3 - A3*B2
FC = ABS( C )
D1 = ONE
IF( FC.NE.ZERO )
$ D1 = C / FC
CALL SLASV2( A, FC, D, S1, S2, SNR, CSR, SNL, CSL )
IF( ABS( CSR ).GE.ABS( SNR ) .OR. ABS( CSL ).GE.ABS( SNL ) )
$ THEN
UA21 = -D1*SNR*A1 + CSR*A2
UA22R = CSR*A3
VB21 = -D1*SNL*B1 + CSL*B2
VB22R = CSL*B3
AUA21 = ABS( SNR )*ABS( A1 ) + ABS( CSR )*ABS1( A2 )
AVB21 = ABS( SNL )*ABS( B1 ) + ABS( CSL )*ABS1( B2 )
IF( ( ABS1( UA21 )+ABS( UA22R ) ).EQ.ZERO ) THEN
CALL CLARTG( CMPLX( VB22R ), VB21, CSQ, SNQ, R )
ELSE IF( ( ABS1( VB21 )+ABS( VB22R ) ).EQ.ZERO ) THEN
CALL CLARTG( CMPLX( UA22R ), UA21, CSQ, SNQ, R )
ELSE IF( AUA21 / ( ABS1( UA21 )+ABS( UA22R ) ).LE.AVB21 /
$ ( ABS1( VB21 )+ABS( VB22R ) ) ) THEN
CALL CLARTG( CMPLX( UA22R ), UA21, CSQ, SNQ, R )
ELSE
CALL CLARTG( CMPLX( VB22R ), VB21, CSQ, SNQ, R )
END IF
CSU = CSR
SNU = -CONJG( D1 )*SNR
CSV = CSL
SNV = -CONJG( D1 )*SNL
ELSE
UA11 = CSR*A1 + CONJG( D1 )*SNR*A2
UA12 = CONJG( D1 )*SNR*A3
VB11 = CSL*B1 + CONJG( D1 )*SNL*B2
VB12 = CONJG( D1 )*SNL*B3
AUA11 = ABS( CSR )*ABS( A1 ) + ABS( SNR )*ABS1( A2 )
AVB11 = ABS( CSL )*ABS( B1 ) + ABS( SNL )*ABS1( B2 )
IF( ( ABS1( UA11 )+ABS1( UA12 ) ).EQ.ZERO ) THEN
CALL CLARTG( VB12, VB11, CSQ, SNQ, R )
ELSE IF( ( ABS1( VB11 )+ABS1( VB12 ) ).EQ.ZERO ) THEN
CALL CLARTG( UA12, UA11, CSQ, SNQ, R )
ELSE IF( AUA11 / ( ABS1( UA11 )+ABS1( UA12 ) ).LE.AVB11 /
$ ( ABS1( VB11 )+ABS1( VB12 ) ) ) THEN
CALL CLARTG( UA12, UA11, CSQ, SNQ, R )
ELSE
CALL CLARTG( VB12, VB11, CSQ, SNQ, R )
END IF
CSU = SNR
SNU = CONJG( D1 )*CSR
CSV = SNL
SNV = CONJG( D1 )*CSL
END IF
END IF
RETURN
END