1: *> \brief \b ZUNMTR
2: *
3: * =========== DOCUMENTATION ===========
4: *
5: * Online html documentation available at
6: * http://www.netlib.org/lapack/explore-html/
7: *
8: *> \htmlonly
9: *> Download ZUNMTR + 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/zunmtr.f">
15: *> [TXT]</a>
16: *> \endhtmlonly
17: *
18: * Definition:
19: * ===========
20: *
21: * SUBROUTINE ZUNMTR( SIDE, UPLO, TRANS, M, N, A, LDA, TAU, C, LDC,
22: * WORK, LWORK, INFO )
23: *
24: * .. Scalar Arguments ..
25: * CHARACTER SIDE, TRANS, UPLO
26: * INTEGER 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: *> ZUNMTR 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: *> nq-1 elementary reflectors, as returned by ZHETRD:
47: *>
48: *> if UPLO = 'U', Q = H(nq-1) . . . H(2) H(1);
49: *>
50: *> if UPLO = 'L', Q = H(1) H(2) . . . H(nq-1).
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] UPLO
64: *> \verbatim
65: *> UPLO is CHARACTER*1
66: *> = 'U': Upper triangle of A contains elementary reflectors
67: *> from ZHETRD;
68: *> = 'L': Lower triangle of A contains elementary reflectors
69: *> from ZHETRD.
70: *> \endverbatim
71: *>
72: *> \param[in] TRANS
73: *> \verbatim
74: *> TRANS is CHARACTER*1
75: *> = 'N': No transpose, apply Q;
76: *> = 'C': Conjugate transpose, apply Q**H.
77: *> \endverbatim
78: *>
79: *> \param[in] M
80: *> \verbatim
81: *> M is INTEGER
82: *> The number of rows of the matrix C. M >= 0.
83: *> \endverbatim
84: *>
85: *> \param[in] N
86: *> \verbatim
87: *> N is INTEGER
88: *> The number of columns of the matrix C. N >= 0.
89: *> \endverbatim
90: *>
91: *> \param[in] A
92: *> \verbatim
93: *> A is COMPLEX*16 array, dimension
94: *> (LDA,M) if SIDE = 'L'
95: *> (LDA,N) if SIDE = 'R'
96: *> The vectors which define the elementary reflectors, as
97: *> returned by ZHETRD.
98: *> \endverbatim
99: *>
100: *> \param[in] LDA
101: *> \verbatim
102: *> LDA is INTEGER
103: *> The leading dimension of the array A.
104: *> LDA >= max(1,M) if SIDE = 'L'; LDA >= max(1,N) if SIDE = 'R'.
105: *> \endverbatim
106: *>
107: *> \param[in] TAU
108: *> \verbatim
109: *> TAU is COMPLEX*16 array, dimension
110: *> (M-1) if SIDE = 'L'
111: *> (N-1) if SIDE = 'R'
112: *> TAU(i) must contain the scalar factor of the elementary
113: *> reflector H(i), as returned by ZHETRD.
114: *> \endverbatim
115: *>
116: *> \param[in,out] C
117: *> \verbatim
118: *> C is COMPLEX*16 array, dimension (LDC,N)
119: *> On entry, the M-by-N matrix C.
120: *> On exit, C is overwritten by Q*C or Q**H*C or C*Q**H or C*Q.
121: *> \endverbatim
122: *>
123: *> \param[in] LDC
124: *> \verbatim
125: *> LDC is INTEGER
126: *> The leading dimension of the array C. LDC >= max(1,M).
127: *> \endverbatim
128: *>
129: *> \param[out] WORK
130: *> \verbatim
131: *> WORK is COMPLEX*16 array, dimension (MAX(1,LWORK))
132: *> On exit, if INFO = 0, WORK(1) returns the optimal LWORK.
133: *> \endverbatim
134: *>
135: *> \param[in] LWORK
136: *> \verbatim
137: *> LWORK is INTEGER
138: *> The dimension of the array WORK.
139: *> If SIDE = 'L', LWORK >= max(1,N);
140: *> if SIDE = 'R', LWORK >= max(1,M).
141: *> For optimum performance LWORK >= N*NB if SIDE = 'L', and
142: *> LWORK >=M*NB if SIDE = 'R', where NB is the optimal
143: *> blocksize.
144: *>
145: *> If LWORK = -1, then a workspace query is assumed; the routine
146: *> only calculates the optimal size of the WORK array, returns
147: *> this value as the first entry of the WORK array, and no error
148: *> message related to LWORK is issued by XERBLA.
149: *> \endverbatim
150: *>
151: *> \param[out] INFO
152: *> \verbatim
153: *> INFO is INTEGER
154: *> = 0: successful exit
155: *> < 0: if INFO = -i, the i-th argument had an illegal value
156: *> \endverbatim
157: *
158: * Authors:
159: * ========
160: *
161: *> \author Univ. of Tennessee
162: *> \author Univ. of California Berkeley
163: *> \author Univ. of Colorado Denver
164: *> \author NAG Ltd.
165: *
166: *> \ingroup complex16OTHERcomputational
167: *
168: * =====================================================================
169: SUBROUTINE ZUNMTR( SIDE, UPLO, TRANS, M, N, A, LDA, TAU, C, LDC,
170: $ WORK, LWORK, INFO )
171: *
172: * -- LAPACK computational routine --
173: * -- LAPACK is a software package provided by Univ. of Tennessee, --
174: * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
175: *
176: * .. Scalar Arguments ..
177: CHARACTER SIDE, TRANS, UPLO
178: INTEGER INFO, LDA, LDC, LWORK, M, N
179: * ..
180: * .. Array Arguments ..
181: COMPLEX*16 A( LDA, * ), C( LDC, * ), TAU( * ), WORK( * )
182: * ..
183: *
184: * =====================================================================
185: *
186: * .. Local Scalars ..
187: LOGICAL LEFT, LQUERY, UPPER
188: INTEGER I1, I2, IINFO, LWKOPT, MI, NB, NI, NQ, NW
189: * ..
190: * .. External Functions ..
191: LOGICAL LSAME
192: INTEGER ILAENV
193: EXTERNAL LSAME, ILAENV
194: * ..
195: * .. External Subroutines ..
196: EXTERNAL XERBLA, ZUNMQL, ZUNMQR
197: * ..
198: * .. Intrinsic Functions ..
199: INTRINSIC MAX
200: * ..
201: * .. Executable Statements ..
202: *
203: * Test the input arguments
204: *
205: INFO = 0
206: LEFT = LSAME( SIDE, 'L' )
207: UPPER = LSAME( UPLO, 'U' )
208: LQUERY = ( LWORK.EQ.-1 )
209: *
210: * NQ is the order of Q and NW is the minimum dimension of WORK
211: *
212: IF( LEFT ) THEN
213: NQ = M
214: NW = MAX( 1, N )
215: ELSE
216: NQ = N
217: NW = MAX( 1, M )
218: END IF
219: IF( .NOT.LEFT .AND. .NOT.LSAME( SIDE, 'R' ) ) THEN
220: INFO = -1
221: ELSE IF( .NOT.UPPER .AND. .NOT.LSAME( UPLO, 'L' ) ) THEN
222: INFO = -2
223: ELSE IF( .NOT.LSAME( TRANS, 'N' ) .AND. .NOT.LSAME( TRANS, 'C' ) )
224: $ THEN
225: INFO = -3
226: ELSE IF( M.LT.0 ) THEN
227: INFO = -4
228: ELSE IF( N.LT.0 ) THEN
229: INFO = -5
230: ELSE IF( LDA.LT.MAX( 1, NQ ) ) THEN
231: INFO = -7
232: ELSE IF( LDC.LT.MAX( 1, M ) ) THEN
233: INFO = -10
234: ELSE IF( LWORK.LT.NW .AND. .NOT.LQUERY ) THEN
235: INFO = -12
236: END IF
237: *
238: IF( INFO.EQ.0 ) THEN
239: IF( UPPER ) THEN
240: IF( LEFT ) THEN
241: NB = ILAENV( 1, 'ZUNMQL', SIDE // TRANS, M-1, N, M-1,
242: $ -1 )
243: ELSE
244: NB = ILAENV( 1, 'ZUNMQL', SIDE // TRANS, M, N-1, N-1,
245: $ -1 )
246: END IF
247: ELSE
248: IF( LEFT ) THEN
249: NB = ILAENV( 1, 'ZUNMQR', SIDE // TRANS, M-1, N, M-1,
250: $ -1 )
251: ELSE
252: NB = ILAENV( 1, 'ZUNMQR', SIDE // TRANS, M, N-1, N-1,
253: $ -1 )
254: END IF
255: END IF
256: LWKOPT = NW*NB
257: WORK( 1 ) = LWKOPT
258: END IF
259: *
260: IF( INFO.NE.0 ) THEN
261: CALL XERBLA( 'ZUNMTR', -INFO )
262: RETURN
263: ELSE IF( LQUERY ) THEN
264: RETURN
265: END IF
266: *
267: * Quick return if possible
268: *
269: IF( M.EQ.0 .OR. N.EQ.0 .OR. NQ.EQ.1 ) THEN
270: WORK( 1 ) = 1
271: RETURN
272: END IF
273: *
274: IF( LEFT ) THEN
275: MI = M - 1
276: NI = N
277: ELSE
278: MI = M
279: NI = N - 1
280: END IF
281: *
282: IF( UPPER ) THEN
283: *
284: * Q was determined by a call to ZHETRD with UPLO = 'U'
285: *
286: CALL ZUNMQL( SIDE, TRANS, MI, NI, NQ-1, A( 1, 2 ), LDA, TAU, C,
287: $ LDC, WORK, LWORK, IINFO )
288: ELSE
289: *
290: * Q was determined by a call to ZHETRD with UPLO = 'L'
291: *
292: IF( LEFT ) THEN
293: I1 = 2
294: I2 = 1
295: ELSE
296: I1 = 1
297: I2 = 2
298: END IF
299: CALL ZUNMQR( SIDE, TRANS, MI, NI, NQ-1, A( 2, 1 ), LDA, TAU,
300: $ C( I1, I2 ), LDC, WORK, LWORK, IINFO )
301: END IF
302: WORK( 1 ) = LWKOPT
303: RETURN
304: *
305: * End of ZUNMTR
306: *
307: END
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