SYNOPSIS¶
- SUBROUTINE
ZLAQR1(
- N, H, LDH, S1, S2, V )
COMPLEX*16 S1, S2 INTEGER LDH, N COMPLEX*16 H( LDH, * ), V( * )
COMPLEX*16 ZERO PARAMETER ( ZERO = ( 0.0d0, 0.0d0 ) ) DOUBLE PRECISION RZERO
PARAMETER ( RZERO = 0.0d0 ) COMPLEX*16 CDUM, H21S, H31S DOUBLE PRECISION S
INTRINSIC ABS, DBLE, DIMAG DOUBLE PRECISION CABS1 CABS1( CDUM ) = ABS( DBLE(
CDUM ) ) + ABS( DIMAG( 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