186 SUBROUTINE zgebd2( M, N, A, LDA, D, E, TAUQ, TAUP, WORK, INFO )
193 INTEGER INFO, LDA, M, N
196 DOUBLE PRECISION D( * ), E( * )
197 COMPLEX*16 A( LDA, * ), TAUP( * ), TAUQ( * ), WORK( * )
204 parameter( zero = ( 0.0d+0, 0.0d+0 ) )
213 INTRINSIC dconjg, max, min
222 ELSE IF( n.LT.0 )
THEN
224 ELSE IF( lda.LT.max( 1, m ) )
THEN
228 CALL xerbla(
'ZGEBD2', -info )
241 CALL zlarfg( m-i+1, alpha, a( min( i+1, m ), i ), 1,
243 d( i ) = dble( alpha )
248 $
CALL zlarf1f(
'Left', m-i+1, n-i, a( i, i ), 1,
249 $ dconjg( tauq( i ) ), a( i, i+1 ), lda, work )
257 CALL zlacgv( n-i, a( i, i+1 ), lda )
259 CALL zlarfg( n-i, alpha, a( i, min( i+2, n ) ), lda,
261 e( i ) = dble( alpha )
265 CALL zlarf1f(
'Right', m-i, n-i, a( i, i+1 ), lda,
266 $ taup( i ), a( i+1, i+1 ), lda, work )
267 CALL zlacgv( n-i, a( i, i+1 ), lda )
281 CALL zlacgv( n-i+1, a( i, i ), lda )
283 CALL zlarfg( n-i+1, alpha, a( i, min( i+1, n ) ), lda,
285 d( i ) = dble( alpha )
290 $
CALL zlarf1f(
'Right', m-i, n-i+1, a( i, i ), lda,
291 $ taup( i ), a( i+1, i ), lda, work )
292 CALL zlacgv( n-i+1, a( i, i ), lda )
301 CALL zlarfg( m-i, alpha, a( min( i+2, m ), i ), 1,
303 e( i ) = dble( alpha )
307 CALL zlarf1f(
'Left', m-i, n-i, a( i+1, i ), 1,
308 $ dconjg( tauq( i ) ), a( i+1, i+1 ), lda,
subroutine zgebd2(m, n, a, lda, d, e, tauq, taup, work, info)
ZGEBD2 reduces a general matrix to bidiagonal form using an unblocked algorithm.
subroutine zlarf1f(side, m, n, v, incv, tau, c, ldc, work)
ZLARF1F applies an elementary reflector to a general rectangular