128 SUBROUTINE dgelq2( M, N, A, LDA, TAU, WORK, INFO )
135 INTEGER INFO, LDA, M, N
138 DOUBLE PRECISION A( LDA, * ), TAU( * ), WORK( * )
145 parameter( one = 1.0d+0 )
164 ELSE IF( n.LT.0 )
THEN
166 ELSE IF( lda.LT.max( 1, m ) )
THEN
170 CALL xerbla(
'DGELQ2', -info )
180 CALL dlarfg( n-i+1, a( i, i ), a( i, min( i+1, n ) ), lda,
188 CALL dlarf(
'Right', m-i, n-i+1, a( i, i ), lda, tau( i ),
189 $ a( i+1, i ), lda, work )
subroutine xerbla(SRNAME, INFO)
XERBLA
subroutine dgelq2(M, N, A, LDA, TAU, WORK, INFO)
DGELQ2 computes the LQ factorization of a general rectangular matrix using an unblocked algorithm.
subroutine dlarf(SIDE, M, N, V, INCV, TAU, C, LDC, WORK)
DLARF applies an elementary reflector to a general rectangular matrix.
subroutine dlarfg(N, ALPHA, X, INCX, TAU)
DLARFG generates an elementary reflector (Householder matrix).