128 SUBROUTINE dgeqrt2( M, N, A, LDA, T, LDT, INFO )
136 INTEGER INFO, LDA, LDT, M, N
139 DOUBLE PRECISION A( lda, * ), T( ldt, * )
145 DOUBLE PRECISION ONE, ZERO
146 parameter( one = 1.0d+00, zero = 0.0d+00 )
150 DOUBLE PRECISION AII, ALPHA
162 ELSE IF( n.LT.0 )
THEN
164 ELSE IF( lda.LT.max( 1, m ) )
THEN
166 ELSE IF( ldt.LT.max( 1, n ) )
THEN
170 CALL
xerbla(
'DGEQRT2', -info )
180 CALL
dlarfg( m-i+1, a( i, i ), a( min( i+1, m ), i ), 1,
191 CALL
dgemv(
'T',m-i+1, n-i, one, a( i, i+1 ), lda,
192 $ a( i, i ), 1, zero, t( 1, n ), 1 )
197 CALL
dger( m-i+1, n-i, alpha, a( i, i ), 1,
198 $ t( 1, n ), 1, a( i, i+1 ), lda )
210 CALL
dgemv(
'T', m-i+1, i-1, alpha, a( i, 1 ), lda,
211 $ a( i, i ), 1, zero, t( 1, i ), 1 )
216 CALL
dtrmv(
'U',
'N',
'N', i-1, t, ldt, t( 1, i ), 1 )
220 t( i, i ) = t( i, 1 )
subroutine dger(M, N, ALPHA, X, INCX, Y, INCY, A, LDA)
DGER
subroutine dgeqrt2(M, N, A, LDA, T, LDT, INFO)
DGEQRT2 computes a QR factorization of a general real or complex matrix using the compact WY represen...
subroutine dlarfg(N, ALPHA, X, INCX, TAU)
DLARFG generates an elementary reflector (Householder matrix).
subroutine xerbla(SRNAME, INFO)
XERBLA
subroutine dgemv(TRANS, M, N, ALPHA, A, LDA, X, INCX, BETA, Y, INCY)
DGEMV
subroutine dtrmv(UPLO, TRANS, DIAG, N, A, LDA, X, INCX)
DTRMV