122 SUBROUTINE cgeqr2( M, N, A, LDA, TAU, WORK, INFO )
130 INTEGER INFO, LDA, M, N
133 COMPLEX A( lda, * ), TAU( * ), WORK( * )
140 parameter( one = ( 1.0e+0, 0.0e+0 ) )
150 INTRINSIC conjg, max, min
159 ELSE IF( n.LT.0 )
THEN
161 ELSE IF( lda.LT.max( 1, m ) )
THEN
165 CALL
xerbla(
'CGEQR2', -info )
175 CALL
clarfg( m-i+1, a( i, i ), a( min( i+1, m ), i ), 1,
183 CALL
clarf(
'Left', m-i+1, n-i, a( i, i ), 1,
184 $ conjg( tau( i ) ), a( i, i+1 ), lda, work )
subroutine xerbla(SRNAME, INFO)
XERBLA
subroutine cgeqr2(M, N, A, LDA, TAU, WORK, INFO)
CGEQR2 computes the QR factorization of a general rectangular matrix using an unblocked algorithm...
subroutine clarfg(N, ALPHA, X, INCX, TAU)
CLARFG generates an elementary reflector (Householder matrix).
subroutine clarf(SIDE, M, N, V, INCV, TAU, C, LDC, WORK)
CLARF applies an elementary reflector to a general rectangular matrix.