Annotation of rpl/lapack/lapack/zunmtr.f, revision 1.3
1.1 bertrand 1: SUBROUTINE ZUNMTR( SIDE, UPLO, TRANS, M, N, A, LDA, TAU, C, LDC,
2: $ WORK, LWORK, INFO )
3: *
4: * -- LAPACK routine (version 3.2) --
5: * -- LAPACK is a software package provided by Univ. of Tennessee, --
6: * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
7: * November 2006
8: *
9: * .. Scalar Arguments ..
10: CHARACTER SIDE, TRANS, UPLO
11: INTEGER INFO, LDA, LDC, LWORK, M, N
12: * ..
13: * .. Array Arguments ..
14: COMPLEX*16 A( LDA, * ), C( LDC, * ), TAU( * ), WORK( * )
15: * ..
16: *
17: * Purpose
18: * =======
19: *
20: * ZUNMTR overwrites the general complex M-by-N matrix C with
21: *
22: * SIDE = 'L' SIDE = 'R'
23: * TRANS = 'N': Q * C C * Q
24: * TRANS = 'C': Q**H * C C * Q**H
25: *
26: * where Q is a complex unitary matrix of order nq, with nq = m if
27: * SIDE = 'L' and nq = n if SIDE = 'R'. Q is defined as the product of
28: * nq-1 elementary reflectors, as returned by ZHETRD:
29: *
30: * if UPLO = 'U', Q = H(nq-1) . . . H(2) H(1);
31: *
32: * if UPLO = 'L', Q = H(1) H(2) . . . H(nq-1).
33: *
34: * Arguments
35: * =========
36: *
37: * SIDE (input) CHARACTER*1
38: * = 'L': apply Q or Q**H from the Left;
39: * = 'R': apply Q or Q**H from the Right.
40: *
41: * UPLO (input) CHARACTER*1
42: * = 'U': Upper triangle of A contains elementary reflectors
43: * from ZHETRD;
44: * = 'L': Lower triangle of A contains elementary reflectors
45: * from ZHETRD.
46: *
47: * TRANS (input) CHARACTER*1
48: * = 'N': No transpose, apply Q;
49: * = 'C': Conjugate transpose, apply Q**H.
50: *
51: * M (input) INTEGER
52: * The number of rows of the matrix C. M >= 0.
53: *
54: * N (input) INTEGER
55: * The number of columns of the matrix C. N >= 0.
56: *
57: * A (input) COMPLEX*16 array, dimension
58: * (LDA,M) if SIDE = 'L'
59: * (LDA,N) if SIDE = 'R'
60: * The vectors which define the elementary reflectors, as
61: * returned by ZHETRD.
62: *
63: * LDA (input) INTEGER
64: * The leading dimension of the array A.
65: * LDA >= max(1,M) if SIDE = 'L'; LDA >= max(1,N) if SIDE = 'R'.
66: *
67: * TAU (input) COMPLEX*16 array, dimension
68: * (M-1) if SIDE = 'L'
69: * (N-1) if SIDE = 'R'
70: * TAU(i) must contain the scalar factor of the elementary
71: * reflector H(i), as returned by ZHETRD.
72: *
73: * C (input/output) COMPLEX*16 array, dimension (LDC,N)
74: * On entry, the M-by-N matrix C.
75: * On exit, C is overwritten by Q*C or Q**H*C or C*Q**H or C*Q.
76: *
77: * LDC (input) INTEGER
78: * The leading dimension of the array C. LDC >= max(1,M).
79: *
80: * WORK (workspace/output) COMPLEX*16 array, dimension (MAX(1,LWORK))
81: * On exit, if INFO = 0, WORK(1) returns the optimal LWORK.
82: *
83: * LWORK (input) INTEGER
84: * The dimension of the array WORK.
85: * If SIDE = 'L', LWORK >= max(1,N);
86: * if SIDE = 'R', LWORK >= max(1,M).
87: * For optimum performance LWORK >= N*NB if SIDE = 'L', and
88: * LWORK >=M*NB if SIDE = 'R', where NB is the optimal
89: * blocksize.
90: *
91: * If LWORK = -1, then a workspace query is assumed; the routine
92: * only calculates the optimal size of the WORK array, returns
93: * this value as the first entry of the WORK array, and no error
94: * message related to LWORK is issued by XERBLA.
95: *
96: * INFO (output) INTEGER
97: * = 0: successful exit
98: * < 0: if INFO = -i, the i-th argument had an illegal value
99: *
100: * =====================================================================
101: *
102: * .. Local Scalars ..
103: LOGICAL LEFT, LQUERY, UPPER
104: INTEGER I1, I2, IINFO, LWKOPT, MI, NB, NI, NQ, NW
105: * ..
106: * .. External Functions ..
107: LOGICAL LSAME
108: INTEGER ILAENV
109: EXTERNAL LSAME, ILAENV
110: * ..
111: * .. External Subroutines ..
112: EXTERNAL XERBLA, ZUNMQL, ZUNMQR
113: * ..
114: * .. Intrinsic Functions ..
115: INTRINSIC MAX
116: * ..
117: * .. Executable Statements ..
118: *
119: * Test the input arguments
120: *
121: INFO = 0
122: LEFT = LSAME( SIDE, 'L' )
123: UPPER = LSAME( UPLO, 'U' )
124: LQUERY = ( LWORK.EQ.-1 )
125: *
126: * NQ is the order of Q and NW is the minimum dimension of WORK
127: *
128: IF( LEFT ) THEN
129: NQ = M
130: NW = N
131: ELSE
132: NQ = N
133: NW = M
134: END IF
135: IF( .NOT.LEFT .AND. .NOT.LSAME( SIDE, 'R' ) ) THEN
136: INFO = -1
137: ELSE IF( .NOT.UPPER .AND. .NOT.LSAME( UPLO, 'L' ) ) THEN
138: INFO = -2
139: ELSE IF( .NOT.LSAME( TRANS, 'N' ) .AND. .NOT.LSAME( TRANS, 'C' ) )
140: $ THEN
141: INFO = -3
142: ELSE IF( M.LT.0 ) THEN
143: INFO = -4
144: ELSE IF( N.LT.0 ) THEN
145: INFO = -5
146: ELSE IF( LDA.LT.MAX( 1, NQ ) ) THEN
147: INFO = -7
148: ELSE IF( LDC.LT.MAX( 1, M ) ) THEN
149: INFO = -10
150: ELSE IF( LWORK.LT.MAX( 1, NW ) .AND. .NOT.LQUERY ) THEN
151: INFO = -12
152: END IF
153: *
154: IF( INFO.EQ.0 ) THEN
155: IF( UPPER ) THEN
156: IF( LEFT ) THEN
157: NB = ILAENV( 1, 'ZUNMQL', SIDE // TRANS, M-1, N, M-1,
158: $ -1 )
159: ELSE
160: NB = ILAENV( 1, 'ZUNMQL', SIDE // TRANS, M, N-1, N-1,
161: $ -1 )
162: END IF
163: ELSE
164: IF( LEFT ) THEN
165: NB = ILAENV( 1, 'ZUNMQR', SIDE // TRANS, M-1, N, M-1,
166: $ -1 )
167: ELSE
168: NB = ILAENV( 1, 'ZUNMQR', SIDE // TRANS, M, N-1, N-1,
169: $ -1 )
170: END IF
171: END IF
172: LWKOPT = MAX( 1, NW )*NB
173: WORK( 1 ) = LWKOPT
174: END IF
175: *
176: IF( INFO.NE.0 ) THEN
177: CALL XERBLA( 'ZUNMTR', -INFO )
178: RETURN
179: ELSE IF( LQUERY ) THEN
180: RETURN
181: END IF
182: *
183: * Quick return if possible
184: *
185: IF( M.EQ.0 .OR. N.EQ.0 .OR. NQ.EQ.1 ) THEN
186: WORK( 1 ) = 1
187: RETURN
188: END IF
189: *
190: IF( LEFT ) THEN
191: MI = M - 1
192: NI = N
193: ELSE
194: MI = M
195: NI = N - 1
196: END IF
197: *
198: IF( UPPER ) THEN
199: *
200: * Q was determined by a call to ZHETRD with UPLO = 'U'
201: *
202: CALL ZUNMQL( SIDE, TRANS, MI, NI, NQ-1, A( 1, 2 ), LDA, TAU, C,
203: $ LDC, WORK, LWORK, IINFO )
204: ELSE
205: *
206: * Q was determined by a call to ZHETRD with UPLO = 'L'
207: *
208: IF( LEFT ) THEN
209: I1 = 2
210: I2 = 1
211: ELSE
212: I1 = 1
213: I2 = 2
214: END IF
215: CALL ZUNMQR( SIDE, TRANS, MI, NI, NQ-1, A( 2, 1 ), LDA, TAU,
216: $ C( I1, I2 ), LDC, WORK, LWORK, IINFO )
217: END IF
218: WORK( 1 ) = LWKOPT
219: RETURN
220: *
221: * End of ZUNMTR
222: *
223: END
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