Annotation of rpl/lapack/lapack/zlatzm.f, revision 1.18
1.9 bertrand 1: *> \brief \b ZLATZM
2: *
3: * =========== DOCUMENTATION ===========
4: *
1.15 bertrand 5: * Online html documentation available at
6: * http://www.netlib.org/lapack/explore-html/
1.9 bertrand 7: *
8: *> \htmlonly
1.15 bertrand 9: *> Download ZLATZM + 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/zlatzm.f">
1.9 bertrand 15: *> [TXT]</a>
1.15 bertrand 16: *> \endhtmlonly
1.9 bertrand 17: *
18: * Definition:
19: * ===========
20: *
21: * SUBROUTINE ZLATZM( SIDE, M, N, V, INCV, TAU, C1, C2, LDC, WORK )
1.15 bertrand 22: *
1.9 bertrand 23: * .. Scalar Arguments ..
24: * CHARACTER SIDE
25: * INTEGER INCV, LDC, M, N
26: * COMPLEX*16 TAU
27: * ..
28: * .. Array Arguments ..
29: * COMPLEX*16 C1( LDC, * ), C2( LDC, * ), V( * ), WORK( * )
30: * ..
1.15 bertrand 31: *
1.9 bertrand 32: *
33: *> \par Purpose:
34: * =============
35: *>
36: *> \verbatim
37: *>
38: *> This routine is deprecated and has been replaced by routine ZUNMRZ.
39: *>
40: *> ZLATZM applies a Householder matrix generated by ZTZRQF to a matrix.
41: *>
42: *> Let P = I - tau*u*u**H, u = ( 1 ),
43: *> ( v )
44: *> where v is an (m-1) vector if SIDE = 'L', or a (n-1) vector if
45: *> SIDE = 'R'.
46: *>
47: *> If SIDE equals 'L', let
48: *> C = [ C1 ] 1
49: *> [ C2 ] m-1
50: *> n
51: *> Then C is overwritten by P*C.
52: *>
53: *> If SIDE equals 'R', let
54: *> C = [ C1, C2 ] m
55: *> 1 n-1
56: *> Then C is overwritten by C*P.
57: *> \endverbatim
58: *
59: * Arguments:
60: * ==========
61: *
62: *> \param[in] SIDE
63: *> \verbatim
64: *> SIDE is CHARACTER*1
65: *> = 'L': form P * C
66: *> = 'R': form C * P
67: *> \endverbatim
68: *>
69: *> \param[in] M
70: *> \verbatim
71: *> M is INTEGER
72: *> The number of rows of the matrix C.
73: *> \endverbatim
74: *>
75: *> \param[in] N
76: *> \verbatim
77: *> N is INTEGER
78: *> The number of columns of the matrix C.
79: *> \endverbatim
80: *>
81: *> \param[in] V
82: *> \verbatim
83: *> V is COMPLEX*16 array, dimension
84: *> (1 + (M-1)*abs(INCV)) if SIDE = 'L'
85: *> (1 + (N-1)*abs(INCV)) if SIDE = 'R'
86: *> The vector v in the representation of P. V is not used
87: *> if TAU = 0.
88: *> \endverbatim
89: *>
90: *> \param[in] INCV
91: *> \verbatim
92: *> INCV is INTEGER
93: *> The increment between elements of v. INCV <> 0
94: *> \endverbatim
95: *>
96: *> \param[in] TAU
97: *> \verbatim
98: *> TAU is COMPLEX*16
99: *> The value tau in the representation of P.
100: *> \endverbatim
101: *>
102: *> \param[in,out] C1
103: *> \verbatim
104: *> C1 is COMPLEX*16 array, dimension
105: *> (LDC,N) if SIDE = 'L'
106: *> (M,1) if SIDE = 'R'
107: *> On entry, the n-vector C1 if SIDE = 'L', or the m-vector C1
108: *> if SIDE = 'R'.
109: *>
110: *> On exit, the first row of P*C if SIDE = 'L', or the first
111: *> column of C*P if SIDE = 'R'.
112: *> \endverbatim
113: *>
114: *> \param[in,out] C2
115: *> \verbatim
116: *> C2 is COMPLEX*16 array, dimension
117: *> (LDC, N) if SIDE = 'L'
118: *> (LDC, N-1) if SIDE = 'R'
119: *> On entry, the (m - 1) x n matrix C2 if SIDE = 'L', or the
120: *> m x (n - 1) matrix C2 if SIDE = 'R'.
121: *>
122: *> On exit, rows 2:m of P*C if SIDE = 'L', or columns 2:m of C*P
123: *> if SIDE = 'R'.
124: *> \endverbatim
125: *>
126: *> \param[in] LDC
127: *> \verbatim
128: *> LDC is INTEGER
129: *> The leading dimension of the arrays C1 and C2.
130: *> LDC >= max(1,M).
131: *> \endverbatim
132: *>
133: *> \param[out] WORK
134: *> \verbatim
135: *> WORK is COMPLEX*16 array, dimension
136: *> (N) if SIDE = 'L'
137: *> (M) if SIDE = 'R'
138: *> \endverbatim
139: *
140: * Authors:
141: * ========
142: *
1.15 bertrand 143: *> \author Univ. of Tennessee
144: *> \author Univ. of California Berkeley
145: *> \author Univ. of Colorado Denver
146: *> \author NAG Ltd.
1.9 bertrand 147: *
148: *> \ingroup complex16OTHERcomputational
149: *
150: * =====================================================================
1.1 bertrand 151: SUBROUTINE ZLATZM( SIDE, M, N, V, INCV, TAU, C1, C2, LDC, WORK )
152: *
1.18 ! bertrand 153: * -- LAPACK computational routine --
1.1 bertrand 154: * -- LAPACK is a software package provided by Univ. of Tennessee, --
155: * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
156: *
157: * .. Scalar Arguments ..
158: CHARACTER SIDE
159: INTEGER INCV, LDC, M, N
160: COMPLEX*16 TAU
161: * ..
162: * .. Array Arguments ..
163: COMPLEX*16 C1( LDC, * ), C2( LDC, * ), V( * ), WORK( * )
164: * ..
165: *
166: * =====================================================================
167: *
168: * .. Parameters ..
169: COMPLEX*16 ONE, ZERO
170: PARAMETER ( ONE = ( 1.0D+0, 0.0D+0 ),
171: $ ZERO = ( 0.0D+0, 0.0D+0 ) )
172: * ..
173: * .. External Subroutines ..
174: EXTERNAL ZAXPY, ZCOPY, ZGEMV, ZGERC, ZGERU, ZLACGV
175: * ..
176: * .. External Functions ..
177: LOGICAL LSAME
178: EXTERNAL LSAME
179: * ..
180: * .. Intrinsic Functions ..
181: INTRINSIC MIN
182: * ..
183: * .. Executable Statements ..
184: *
185: IF( ( MIN( M, N ).EQ.0 ) .OR. ( TAU.EQ.ZERO ) )
186: $ RETURN
187: *
188: IF( LSAME( SIDE, 'L' ) ) THEN
189: *
1.8 bertrand 190: * w := ( C1 + v**H * C2 )**H
1.1 bertrand 191: *
192: CALL ZCOPY( N, C1, LDC, WORK, 1 )
193: CALL ZLACGV( N, WORK, 1 )
194: CALL ZGEMV( 'Conjugate transpose', M-1, N, ONE, C2, LDC, V,
195: $ INCV, ONE, WORK, 1 )
196: *
1.8 bertrand 197: * [ C1 ] := [ C1 ] - tau* [ 1 ] * w**H
1.1 bertrand 198: * [ C2 ] [ C2 ] [ v ]
199: *
200: CALL ZLACGV( N, WORK, 1 )
201: CALL ZAXPY( N, -TAU, WORK, 1, C1, LDC )
202: CALL ZGERU( M-1, N, -TAU, V, INCV, WORK, 1, C2, LDC )
203: *
204: ELSE IF( LSAME( SIDE, 'R' ) ) THEN
205: *
206: * w := C1 + C2 * v
207: *
208: CALL ZCOPY( M, C1, 1, WORK, 1 )
209: CALL ZGEMV( 'No transpose', M, N-1, ONE, C2, LDC, V, INCV, ONE,
210: $ WORK, 1 )
211: *
1.8 bertrand 212: * [ C1, C2 ] := [ C1, C2 ] - tau* w * [ 1 , v**H]
1.1 bertrand 213: *
214: CALL ZAXPY( M, -TAU, WORK, 1, C1, 1 )
215: CALL ZGERC( M, N-1, -TAU, WORK, 1, V, INCV, C2, LDC )
216: END IF
217: *
218: RETURN
219: *
220: * End of ZLATZM
221: *
222: END
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