claqr1(l) - Linux man page
Name
Synopsis
- SUBROUTINE CLAQR1(
N, H, LDH, S1, S2, V )
COMPLEX
S1, S2
INTEGER
LDH, N
COMPLEX
H( LDH, * ), V( * )
COMPLEX
ZERO
PARAMETER
( ZERO = ( 0.0e0, 0.0e0 ) )
REAL
RZERO
PARAMETER
( RZERO = 0.0e0 )
COMPLEX
CDUM, H21S, H31S
REAL
S
INTRINSIC
ABS, AIMAG, REAL
REAL
CABS1
CABS1(
CDUM ) = ABS( REAL( CDUM ) ) + ABS( AIMAG( CDUM ) )
IF(
N.EQ.2 ) THEN
S
= CABS1( H( 1, 1 )-S2 ) + CABS1( H( 2, 1 ) )
IF(
S.EQ.RZERO ) THEN
V(
1 ) = ZERO
V(
2 ) = ZERO
ELSE
H21S
= H( 2, 1 ) / S
V(
1 ) = H21S*H( 1, 2 ) + ( H( 1, 1 )-S1 )* ( ( H( 1, 1 )-S2 ) / S )
V(
2 ) = H21S*( H( 1, 1 )+H( 2, 2 )-S1-S2 )
END
IF
ELSE
S
= CABS1( H( 1, 1 )-S2 ) + CABS1( H( 2, 1 ) ) + CABS1( H( 3, 1 ) )
IF(
S.EQ.ZERO ) THEN
V(
1 ) = ZERO
V(
2 ) = ZERO
V(
3 ) = ZERO
ELSE
H21S
= H( 2, 1 ) / S
H31S
= H( 3, 1 ) / S
V(
1 ) = ( H( 1, 1 )-S1 )*( ( H( 1, 1 )-S2 ) / S ) + H( 1, 2 )*H21S + H( 1, 3 )*H31S
V(
2 ) = H21S*( H( 1, 1 )+H( 2, 2 )-S1-S2 ) + H( 2, 3 )*H31S
V(
3 ) = H31S*( H( 1, 1 )+H( 3, 3 )-S1-S2 ) + H21S*H( 3, 2 )
END
IF
END
IF
END