LAPACK 3.12.0 LAPACK: Linear Algebra PACKage
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zunmhr.f
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1*> \brief \b ZUNMHR
2*
3* =========== DOCUMENTATION ===========
4*
5* Online html documentation available at
6* http://www.netlib.org/lapack/explore-html/
7*
8*> \htmlonly
10*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/zunmhr.f">
11*> [TGZ]</a>
12*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/zunmhr.f">
13*> [ZIP]</a>
14*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/zunmhr.f">
15*> [TXT]</a>
16*> \endhtmlonly
17*
18* Definition:
19* ===========
20*
21* SUBROUTINE ZUNMHR( SIDE, TRANS, M, N, ILO, IHI, A, LDA, TAU, C,
22* LDC, WORK, LWORK, INFO )
23*
24* .. Scalar Arguments ..
25* CHARACTER SIDE, TRANS
26* INTEGER IHI, ILO, INFO, LDA, LDC, LWORK, M, N
27* ..
28* .. Array Arguments ..
29* COMPLEX*16 A( LDA, * ), C( LDC, * ), TAU( * ), WORK( * )
30* ..
31*
32*
33*> \par Purpose:
34* =============
35*>
36*> \verbatim
37*>
38*> ZUNMHR overwrites the general complex M-by-N matrix C with
39*>
40*> SIDE = 'L' SIDE = 'R'
41*> TRANS = 'N': Q * C C * Q
42*> TRANS = 'C': Q**H * C C * Q**H
43*>
44*> where Q is a complex unitary matrix of order nq, with nq = m if
45*> SIDE = 'L' and nq = n if SIDE = 'R'. Q is defined as the product of
46*> IHI-ILO elementary reflectors, as returned by ZGEHRD:
47*>
48*> Q = H(ilo) H(ilo+1) . . . H(ihi-1).
49*> \endverbatim
50*
51* Arguments:
52* ==========
53*
54*> \param[in] SIDE
55*> \verbatim
56*> SIDE is CHARACTER*1
57*> = 'L': apply Q or Q**H from the Left;
58*> = 'R': apply Q or Q**H from the Right.
59*> \endverbatim
60*>
61*> \param[in] TRANS
62*> \verbatim
63*> TRANS is CHARACTER*1
64*> = 'N': apply Q (No transpose)
65*> = 'C': apply Q**H (Conjugate transpose)
66*> \endverbatim
67*>
68*> \param[in] M
69*> \verbatim
70*> M is INTEGER
71*> The number of rows of the matrix C. M >= 0.
72*> \endverbatim
73*>
74*> \param[in] N
75*> \verbatim
76*> N is INTEGER
77*> The number of columns of the matrix C. N >= 0.
78*> \endverbatim
79*>
80*> \param[in] ILO
81*> \verbatim
82*> ILO is INTEGER
83*> \endverbatim
84*>
85*> \param[in] IHI
86*> \verbatim
87*> IHI is INTEGER
88*>
89*> ILO and IHI must have the same values as in the previous call
90*> of ZGEHRD. Q is equal to the unit matrix except in the
91*> submatrix Q(ilo+1:ihi,ilo+1:ihi).
92*> If SIDE = 'L', then 1 <= ILO <= IHI <= M, if M > 0, and
93*> ILO = 1 and IHI = 0, if M = 0;
94*> if SIDE = 'R', then 1 <= ILO <= IHI <= N, if N > 0, and
95*> ILO = 1 and IHI = 0, if N = 0.
96*> \endverbatim
97*>
98*> \param[in] A
99*> \verbatim
100*> A is COMPLEX*16 array, dimension
101*> (LDA,M) if SIDE = 'L'
102*> (LDA,N) if SIDE = 'R'
103*> The vectors which define the elementary reflectors, as
104*> returned by ZGEHRD.
105*> \endverbatim
106*>
107*> \param[in] LDA
108*> \verbatim
109*> LDA is INTEGER
110*> The leading dimension of the array A.
111*> LDA >= max(1,M) if SIDE = 'L'; LDA >= max(1,N) if SIDE = 'R'.
112*> \endverbatim
113*>
114*> \param[in] TAU
115*> \verbatim
116*> TAU is COMPLEX*16 array, dimension
117*> (M-1) if SIDE = 'L'
118*> (N-1) if SIDE = 'R'
119*> TAU(i) must contain the scalar factor of the elementary
120*> reflector H(i), as returned by ZGEHRD.
121*> \endverbatim
122*>
123*> \param[in,out] C
124*> \verbatim
125*> C is COMPLEX*16 array, dimension (LDC,N)
126*> On entry, the M-by-N matrix C.
127*> On exit, C is overwritten by Q*C or Q**H*C or C*Q**H or C*Q.
128*> \endverbatim
129*>
130*> \param[in] LDC
131*> \verbatim
132*> LDC is INTEGER
133*> The leading dimension of the array C. LDC >= max(1,M).
134*> \endverbatim
135*>
136*> \param[out] WORK
137*> \verbatim
138*> WORK is COMPLEX*16 array, dimension (MAX(1,LWORK))
139*> On exit, if INFO = 0, WORK(1) returns the optimal LWORK.
140*> \endverbatim
141*>
142*> \param[in] LWORK
143*> \verbatim
144*> LWORK is INTEGER
145*> The dimension of the array WORK.
146*> If SIDE = 'L', LWORK >= max(1,N);
147*> if SIDE = 'R', LWORK >= max(1,M).
148*> For optimum performance LWORK >= N*NB if SIDE = 'L', and
149*> LWORK >= M*NB if SIDE = 'R', where NB is the optimal
150*> blocksize.
151*>
152*> If LWORK = -1, then a workspace query is assumed; the routine
153*> only calculates the optimal size of the WORK array, returns
154*> this value as the first entry of the WORK array, and no error
155*> message related to LWORK is issued by XERBLA.
156*> \endverbatim
157*>
158*> \param[out] INFO
159*> \verbatim
160*> INFO is INTEGER
161*> = 0: successful exit
162*> < 0: if INFO = -i, the i-th argument had an illegal value
163*> \endverbatim
164*
165* Authors:
166* ========
167*
168*> \author Univ. of Tennessee
169*> \author Univ. of California Berkeley
170*> \author Univ. of Colorado Denver
171*> \author NAG Ltd.
172*
173*> \ingroup unmhr
174*
175* =====================================================================
176 SUBROUTINE zunmhr( SIDE, TRANS, M, N, ILO, IHI, A, LDA, TAU, C,
177 \$ LDC, WORK, LWORK, INFO )
178*
179* -- LAPACK computational routine --
180* -- LAPACK is a software package provided by Univ. of Tennessee, --
181* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
182*
183* .. Scalar Arguments ..
184 CHARACTER SIDE, TRANS
185 INTEGER IHI, ILO, INFO, LDA, LDC, LWORK, M, N
186* ..
187* .. Array Arguments ..
188 COMPLEX*16 A( LDA, * ), C( LDC, * ), TAU( * ), WORK( * )
189* ..
190*
191* =====================================================================
192*
193* .. Local Scalars ..
194 LOGICAL LEFT, LQUERY
195 INTEGER I1, I2, IINFO, LWKOPT, MI, NB, NH, NI, NQ, NW
196* ..
197* .. External Functions ..
198 LOGICAL LSAME
199 INTEGER ILAENV
200 EXTERNAL lsame, ilaenv
201* ..
202* .. External Subroutines ..
203 EXTERNAL xerbla, zunmqr
204* ..
205* .. Intrinsic Functions ..
206 INTRINSIC max, min
207* ..
208* .. Executable Statements ..
209*
210* Test the input arguments
211*
212 info = 0
213 nh = ihi - ilo
214 left = lsame( side, 'L' )
215 lquery = ( lwork.EQ.-1 )
216*
217* NQ is the order of Q and NW is the minimum dimension of WORK
218*
219 IF( left ) THEN
220 nq = m
221 nw = max( 1, n )
222 ELSE
223 nq = n
224 nw = max( 1, m )
225 END IF
226 IF( .NOT.left .AND. .NOT.lsame( side, 'R' ) ) THEN
227 info = -1
228 ELSE IF( .NOT.lsame( trans, 'N' ) .AND. .NOT.lsame( trans, 'C' ) )
229 \$ THEN
230 info = -2
231 ELSE IF( m.LT.0 ) THEN
232 info = -3
233 ELSE IF( n.LT.0 ) THEN
234 info = -4
235 ELSE IF( ilo.LT.1 .OR. ilo.GT.max( 1, nq ) ) THEN
236 info = -5
237 ELSE IF( ihi.LT.min( ilo, nq ) .OR. ihi.GT.nq ) THEN
238 info = -6
239 ELSE IF( lda.LT.max( 1, nq ) ) THEN
240 info = -8
241 ELSE IF( ldc.LT.max( 1, m ) ) THEN
242 info = -11
243 ELSE IF( lwork.LT.nw .AND. .NOT.lquery ) THEN
244 info = -13
245 END IF
246*
247 IF( info.EQ.0 ) THEN
248 IF( left ) THEN
249 nb = ilaenv( 1, 'ZUNMQR', side // trans, nh, n, nh, -1 )
250 ELSE
251 nb = ilaenv( 1, 'ZUNMQR', side // trans, m, nh, nh, -1 )
252 END IF
253 lwkopt = nw*nb
254 work( 1 ) = lwkopt
255 END IF
256*
257 IF( info.NE.0 ) THEN
258 CALL xerbla( 'ZUNMHR', -info )
259 RETURN
260 ELSE IF( lquery ) THEN
261 RETURN
262 END IF
263*
264* Quick return if possible
265*
266 IF( m.EQ.0 .OR. n.EQ.0 .OR. nh.EQ.0 ) THEN
267 work( 1 ) = 1
268 RETURN
269 END IF
270*
271 IF( left ) THEN
272 mi = nh
273 ni = n
274 i1 = ilo + 1
275 i2 = 1
276 ELSE
277 mi = m
278 ni = nh
279 i1 = 1
280 i2 = ilo + 1
281 END IF
282*
283 CALL zunmqr( side, trans, mi, ni, nh, a( ilo+1, ilo ), lda,
284 \$ tau( ilo ), c( i1, i2 ), ldc, work, lwork, iinfo )
285*
286 work( 1 ) = lwkopt
287 RETURN
288*
289* End of ZUNMHR
290*
291 END
subroutine xerbla(srname, info)
Definition cblat2.f:3285
subroutine zunmhr(side, trans, m, n, ilo, ihi, a, lda, tau, c, ldc, work, lwork, info)
ZUNMHR
Definition zunmhr.f:178
subroutine zunmqr(side, trans, m, n, k, a, lda, tau, c, ldc, work, lwork, info)
ZUNMQR
Definition zunmqr.f:167