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