91 DOUBLE PRECISION FUNCTION dtzt02( M, N, AF, LDA, TAU, WORK,
100 INTEGER LDA, LWORK, M, N
103 DOUBLE PRECISION AF( lda, * ), TAU( * ), WORK( lwork )
109 DOUBLE PRECISION ZERO, ONE
110 parameter( zero = 0.0d0, one = 1.0d0 )
116 DOUBLE PRECISION RWORK( 1 )
119 DOUBLE PRECISION DLAMCH, DLANGE
120 EXTERNAL dlamch, dlange
132 IF( lwork.LT.n*n+n )
THEN
133 CALL
xerbla(
'DTZT02', 7 )
139 IF( m.LE.0 .OR. n.LE.0 )
144 CALL
dlaset(
'Full', n, n, zero, one, work, n )
149 CALL
dlatzm(
'Left', n-m+1, n, af( i, m+1 ), lda, tau( i ),
150 $ work( i ), work( m+1 ), n, work( n*n+1 ) )
156 CALL
dlatzm(
'Left', n-m+1, n, af( i, m+1 ), lda, tau( i ),
157 $ work( i ), work( m+1 ), n, work( n*n+1 ) )
163 work( ( i-1 )*n+i ) = work( ( i-1 )*n+i ) - one
166 dtzt02 = dlange(
'One-norm', n, n, work, n, rwork ) /
167 $ ( dlamch(
'Epsilon' )*dble( max( m, n ) ) )
subroutine xerbla(SRNAME, INFO)
XERBLA
subroutine dlatzm(SIDE, M, N, V, INCV, TAU, C1, C2, LDC, WORK)
DLATZM
subroutine dlaset(UPLO, M, N, ALPHA, BETA, A, LDA)
DLASET initializes the off-diagonal elements and the diagonal elements of a matrix to given values...