1: *> \brief \b ZUNMRZ
2: *
3: * =========== DOCUMENTATION ===========
4: *
5: * Online html documentation available at
6: * http://www.netlib.org/lapack/explore-html/
7: *
8: *> \htmlonly
9: *> Download ZUNMRZ + dependencies
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11: *> [TGZ]</a>
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13: *> [ZIP]</a>
14: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/zunmrz.f">
15: *> [TXT]</a>
16: *> \endhtmlonly
17: *
18: * Definition:
19: * ===========
20: *
21: * SUBROUTINE ZUNMRZ( SIDE, TRANS, M, N, K, L, A, LDA, TAU, C, LDC,
22: * WORK, LWORK, INFO )
23: *
24: * .. Scalar Arguments ..
25: * CHARACTER SIDE, TRANS
26: * INTEGER INFO, K, L, 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: *> ZUNMRZ 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 defined as the product of k
45: *> elementary reflectors
46: *>
47: *> Q = H(1) H(2) . . . H(k)
48: *>
49: *> as returned by ZTZRZF. Q is of order M if SIDE = 'L' and of order N
50: *> if SIDE = 'R'.
51: *> \endverbatim
52: *
53: * Arguments:
54: * ==========
55: *
56: *> \param[in] SIDE
57: *> \verbatim
58: *> SIDE is CHARACTER*1
59: *> = 'L': apply Q or Q**H from the Left;
60: *> = 'R': apply Q or Q**H from the Right.
61: *> \endverbatim
62: *>
63: *> \param[in] TRANS
64: *> \verbatim
65: *> TRANS is CHARACTER*1
66: *> = 'N': No transpose, apply Q;
67: *> = 'C': Conjugate transpose, apply Q**H.
68: *> \endverbatim
69: *>
70: *> \param[in] M
71: *> \verbatim
72: *> M is INTEGER
73: *> The number of rows of the matrix C. M >= 0.
74: *> \endverbatim
75: *>
76: *> \param[in] N
77: *> \verbatim
78: *> N is INTEGER
79: *> The number of columns of the matrix C. N >= 0.
80: *> \endverbatim
81: *>
82: *> \param[in] K
83: *> \verbatim
84: *> K is INTEGER
85: *> The number of elementary reflectors whose product defines
86: *> the matrix Q.
87: *> If SIDE = 'L', M >= K >= 0;
88: *> if SIDE = 'R', N >= K >= 0.
89: *> \endverbatim
90: *>
91: *> \param[in] L
92: *> \verbatim
93: *> L is INTEGER
94: *> The number of columns of the matrix A containing
95: *> the meaningful part of the Householder reflectors.
96: *> If SIDE = 'L', M >= L >= 0, if SIDE = 'R', N >= L >= 0.
97: *> \endverbatim
98: *>
99: *> \param[in] A
100: *> \verbatim
101: *> A is COMPLEX*16 array, dimension
102: *> (LDA,M) if SIDE = 'L',
103: *> (LDA,N) if SIDE = 'R'
104: *> The i-th row must contain the vector which defines the
105: *> elementary reflector H(i), for i = 1,2,...,k, as returned by
106: *> ZTZRZF in the last k rows of its array argument A.
107: *> A is modified by the routine but restored on exit.
108: *> \endverbatim
109: *>
110: *> \param[in] LDA
111: *> \verbatim
112: *> LDA is INTEGER
113: *> The leading dimension of the array A. LDA >= max(1,K).
114: *> \endverbatim
115: *>
116: *> \param[in] TAU
117: *> \verbatim
118: *> TAU is COMPLEX*16 array, dimension (K)
119: *> TAU(i) must contain the scalar factor of the elementary
120: *> reflector H(i), as returned by ZTZRZF.
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 good performance, LWORK should generally be larger.
149: *>
150: *> If LWORK = -1, then a workspace query is assumed; the routine
151: *> only calculates the optimal size of the WORK array, returns
152: *> this value as the first entry of the WORK array, and no error
153: *> message related to LWORK is issued by XERBLA.
154: *> \endverbatim
155: *>
156: *> \param[out] INFO
157: *> \verbatim
158: *> INFO is INTEGER
159: *> = 0: successful exit
160: *> < 0: if INFO = -i, the i-th argument had an illegal value
161: *> \endverbatim
162: *
163: * Authors:
164: * ========
165: *
166: *> \author Univ. of Tennessee
167: *> \author Univ. of California Berkeley
168: *> \author Univ. of Colorado Denver
169: *> \author NAG Ltd.
170: *
171: *> \ingroup complex16OTHERcomputational
172: *
173: *> \par Contributors:
174: * ==================
175: *>
176: *> A. Petitet, Computer Science Dept., Univ. of Tenn., Knoxville, USA
177: *
178: *> \par Further Details:
179: * =====================
180: *>
181: *> \verbatim
182: *> \endverbatim
183: *>
184: * =====================================================================
185: SUBROUTINE ZUNMRZ( SIDE, TRANS, M, N, K, L, A, LDA, TAU, C, LDC,
186: $ WORK, LWORK, INFO )
187: *
188: * -- LAPACK computational routine --
189: * -- LAPACK is a software package provided by Univ. of Tennessee, --
190: * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
191: *
192: * .. Scalar Arguments ..
193: CHARACTER SIDE, TRANS
194: INTEGER INFO, K, L, LDA, LDC, LWORK, M, N
195: * ..
196: * .. Array Arguments ..
197: COMPLEX*16 A( LDA, * ), C( LDC, * ), TAU( * ), WORK( * )
198: * ..
199: *
200: * =====================================================================
201: *
202: * .. Parameters ..
203: INTEGER NBMAX, LDT, TSIZE
204: PARAMETER ( NBMAX = 64, LDT = NBMAX+1,
205: $ TSIZE = LDT*NBMAX )
206: * ..
207: * .. Local Scalars ..
208: LOGICAL LEFT, LQUERY, NOTRAN
209: CHARACTER TRANST
210: INTEGER I, I1, I2, I3, IB, IC, IINFO, IWT, JA, JC,
211: $ LDWORK, LWKOPT, MI, NB, NBMIN, NI, NQ, NW
212: * ..
213: * .. External Functions ..
214: LOGICAL LSAME
215: INTEGER ILAENV
216: EXTERNAL LSAME, ILAENV
217: * ..
218: * .. External Subroutines ..
219: EXTERNAL XERBLA, ZLARZB, ZLARZT, ZUNMR3
220: * ..
221: * .. Intrinsic Functions ..
222: INTRINSIC MAX, MIN
223: * ..
224: * .. Executable Statements ..
225: *
226: * Test the input arguments
227: *
228: INFO = 0
229: LEFT = LSAME( SIDE, 'L' )
230: NOTRAN = LSAME( TRANS, 'N' )
231: LQUERY = ( LWORK.EQ.-1 )
232: *
233: * NQ is the order of Q and NW is the minimum dimension of WORK
234: *
235: IF( LEFT ) THEN
236: NQ = M
237: NW = MAX( 1, N )
238: ELSE
239: NQ = N
240: NW = MAX( 1, M )
241: END IF
242: IF( .NOT.LEFT .AND. .NOT.LSAME( SIDE, 'R' ) ) THEN
243: INFO = -1
244: ELSE IF( .NOT.NOTRAN .AND. .NOT.LSAME( TRANS, 'C' ) ) THEN
245: INFO = -2
246: ELSE IF( M.LT.0 ) THEN
247: INFO = -3
248: ELSE IF( N.LT.0 ) THEN
249: INFO = -4
250: ELSE IF( K.LT.0 .OR. K.GT.NQ ) THEN
251: INFO = -5
252: ELSE IF( L.LT.0 .OR. ( LEFT .AND. ( L.GT.M ) ) .OR.
253: $ ( .NOT.LEFT .AND. ( L.GT.N ) ) ) THEN
254: INFO = -6
255: ELSE IF( LDA.LT.MAX( 1, K ) ) THEN
256: INFO = -8
257: ELSE IF( LDC.LT.MAX( 1, M ) ) THEN
258: INFO = -11
259: ELSE IF( LWORK.LT.MAX( 1, NW ) .AND. .NOT.LQUERY ) THEN
260: INFO = -13
261: END IF
262: *
263: IF( INFO.EQ.0 ) THEN
264: *
265: * Compute the workspace requirements
266: *
267: IF( M.EQ.0 .OR. N.EQ.0 ) THEN
268: LWKOPT = 1
269: ELSE
270: NB = MIN( NBMAX, ILAENV( 1, 'ZUNMRQ', SIDE // TRANS, M, N,
271: $ K, -1 ) )
272: LWKOPT = NW*NB + TSIZE
273: END IF
274: WORK( 1 ) = LWKOPT
275: END IF
276: *
277: IF( INFO.NE.0 ) THEN
278: CALL XERBLA( 'ZUNMRZ', -INFO )
279: RETURN
280: ELSE IF( LQUERY ) THEN
281: RETURN
282: END IF
283: *
284: * Quick return if possible
285: *
286: IF( M.EQ.0 .OR. N.EQ.0 ) THEN
287: RETURN
288: END IF
289: *
290: * Determine the block size. NB may be at most NBMAX, where NBMAX
291: * is used to define the local array T.
292: *
293: NB = MIN( NBMAX, ILAENV( 1, 'ZUNMRQ', SIDE // TRANS, M, N, K,
294: $ -1 ) )
295: NBMIN = 2
296: LDWORK = NW
297: IF( NB.GT.1 .AND. NB.LT.K ) THEN
298: IF( LWORK.LT.LWKOPT ) THEN
299: NB = (LWORK-TSIZE) / LDWORK
300: NBMIN = MAX( 2, ILAENV( 2, 'ZUNMRQ', SIDE // TRANS, M, N, K,
301: $ -1 ) )
302: END IF
303: END IF
304: *
305: IF( NB.LT.NBMIN .OR. NB.GE.K ) THEN
306: *
307: * Use unblocked code
308: *
309: CALL ZUNMR3( SIDE, TRANS, M, N, K, L, A, LDA, TAU, C, LDC,
310: $ WORK, IINFO )
311: ELSE
312: *
313: * Use blocked code
314: *
315: IWT = 1 + NW*NB
316: IF( ( LEFT .AND. .NOT.NOTRAN ) .OR.
317: $ ( .NOT.LEFT .AND. NOTRAN ) ) THEN
318: I1 = 1
319: I2 = K
320: I3 = NB
321: ELSE
322: I1 = ( ( K-1 ) / NB )*NB + 1
323: I2 = 1
324: I3 = -NB
325: END IF
326: *
327: IF( LEFT ) THEN
328: NI = N
329: JC = 1
330: JA = M - L + 1
331: ELSE
332: MI = M
333: IC = 1
334: JA = N - L + 1
335: END IF
336: *
337: IF( NOTRAN ) THEN
338: TRANST = 'C'
339: ELSE
340: TRANST = 'N'
341: END IF
342: *
343: DO 10 I = I1, I2, I3
344: IB = MIN( NB, K-I+1 )
345: *
346: * Form the triangular factor of the block reflector
347: * H = H(i+ib-1) . . . H(i+1) H(i)
348: *
349: CALL ZLARZT( 'Backward', 'Rowwise', L, IB, A( I, JA ), LDA,
350: $ TAU( I ), WORK( IWT ), LDT )
351: *
352: IF( LEFT ) THEN
353: *
354: * H or H**H is applied to C(i:m,1:n)
355: *
356: MI = M - I + 1
357: IC = I
358: ELSE
359: *
360: * H or H**H is applied to C(1:m,i:n)
361: *
362: NI = N - I + 1
363: JC = I
364: END IF
365: *
366: * Apply H or H**H
367: *
368: CALL ZLARZB( SIDE, TRANST, 'Backward', 'Rowwise', MI, NI,
369: $ IB, L, A( I, JA ), LDA, WORK( IWT ), LDT,
370: $ C( IC, JC ), LDC, WORK, LDWORK )
371: 10 CONTINUE
372: *
373: END IF
374: *
375: WORK( 1 ) = LWKOPT
376: *
377: RETURN
378: *
379: * End of ZUNMRZ
380: *
381: END
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