129 SUBROUTINE zgeqr2( M, N, A, LDA, TAU, WORK, INFO )
136 INTEGER INFO, LDA, M, N
139 COMPLEX*16 A( LDA, * ), TAU( * ), WORK( * )
146 parameter( one = ( 1.0d+0, 0.0d+0 ) )
156 INTRINSIC dconjg, max, min
165 ELSE IF( n.LT.0 )
THEN
167 ELSE IF( lda.LT.max( 1, m ) )
THEN
171 CALL xerbla(
'ZGEQR2', -info )
181 CALL zlarfg( m-i+1, a( i, i ), a( min( i+1, m ), i ), 1,
189 CALL zlarf(
'Left', m-i+1, n-i, a( i, i ), 1,
190 $ dconjg( tau( i ) ), a( i, i+1 ), lda, work )
subroutine xerbla(SRNAME, INFO)
XERBLA
subroutine zgeqr2(M, N, A, LDA, TAU, WORK, INFO)
ZGEQR2 computes the QR factorization of a general rectangular matrix using an unblocked algorithm.
subroutine zlarf(SIDE, M, N, V, INCV, TAU, C, LDC, WORK)
ZLARF applies an elementary reflector to a general rectangular matrix.
subroutine zlarfg(N, ALPHA, X, INCX, TAU)
ZLARFG generates an elementary reflector (Householder matrix).