SYNOPSIS¶
- SUBROUTINE
DLAQR1(
- N, H, LDH, SR1, SI1, SR2, SI2, V )
DOUBLE PRECISION SI1, SI2, SR1, SR2 INTEGER LDH, N DOUBLE
PRECISION H( LDH, * ), V( * ) DOUBLE PRECISION ZERO PARAMETER ( ZERO = 0.0d0
) DOUBLE PRECISION H21S, H31S, S INTRINSIC ABS IF( N.EQ.2 ) THEN S = ABS( H(
1, 1 )-SR2 ) + ABS( SI2 ) + ABS( H( 2, 1 ) ) IF( S.EQ.ZERO ) THEN V( 1 ) =
ZERO V( 2 ) = ZERO ELSE H21S = H( 2, 1 ) / S V( 1 ) = H21S*H( 1, 2 ) + ( H(
1, 1 )-SR1 )* ( ( H( 1, 1 )-SR2 ) / S ) - SI1*( SI2 / S ) V( 2 ) = H21S*( H(
1, 1 )+H( 2, 2 )-SR1-SR2 ) END IF ELSE S = ABS( H( 1, 1 )-SR2 ) + ABS( SI2 )
+ ABS( H( 2, 1 ) ) + ABS( 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 )-SR1 )*( ( H( 1, 1 )-SR2 ) / S ) - SI1*( SI2 / S ) + H( 1, 2
)*H21S + H( 1, 3 )*H31S V( 2 ) = H21S*( H( 1, 1 )+H( 2, 2 )-SR1-SR2 ) + H(
2, 3 )*H31S V( 3 ) = H31S*( H( 1, 1 )+H( 3, 3 )-SR1-SR2 ) + H21S*H( 3, 2 )
END IF END IF END