1: *> \brief \b ZHETRS_AA_2STAGE
2: *
3: * @generated from SRC/dsytrs_aa_2stage.f, fortran d -> c, Mon Oct 30 11:59:02 2017
4: *
5: * =========== DOCUMENTATION ===========
6: *
7: * Online html documentation available at
8: * http://www.netlib.org/lapack/explore-html/
9: *
10: *> \htmlonly
11: *> Download ZHETRS_AA_2STAGE + dependencies
12: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/zhetrs_aa_2stage.f">
13: *> [TGZ]</a>
14: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/zhetrs_aa_2stage.f">
15: *> [ZIP]</a>
16: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/zhetrs_aa_2stage.f">
17: *> [TXT]</a>
18: *> \endhtmlonly
19: *
20: * Definition:
21: * ===========
22: *
23: * SUBROUTINE ZHETRS_AA_2STAGE( UPLO, N, NRHS, A, LDA, TB, LTB, IPIV,
24: * IPIV2, B, LDB, INFO )
25: *
26: * .. Scalar Arguments ..
27: * CHARACTER UPLO
28: * INTEGER N, NRHS, LDA, LTB, LDB, INFO
29: * ..
30: * .. Array Arguments ..
31: * INTEGER IPIV( * ), IPIV2( * )
32: * COMPLEX*16 A( LDA, * ), TB( * ), B( LDB, * )
33: * ..
34: *
35: *> \par Purpose:
36: * =============
37: *>
38: *> \verbatim
39: *>
40: *> ZHETRS_AA_2STAGE solves a system of linear equations A*X = B with a
41: *> hermitian matrix A using the factorization A = U*T*U**T or
42: *> A = L*T*L**T computed by ZHETRF_AA_2STAGE.
43: *> \endverbatim
44: *
45: * Arguments:
46: * ==========
47: *
48: *> \param[in] UPLO
49: *> \verbatim
50: *> UPLO is CHARACTER*1
51: *> Specifies whether the details of the factorization are stored
52: *> as an upper or lower triangular matrix.
53: *> = 'U': Upper triangular, form is A = U*T*U**T;
54: *> = 'L': Lower triangular, form is A = L*T*L**T.
55: *> \endverbatim
56: *>
57: *> \param[in] N
58: *> \verbatim
59: *> N is INTEGER
60: *> The order of the matrix A. N >= 0.
61: *> \endverbatim
62: *>
63: *> \param[in] NRHS
64: *> \verbatim
65: *> NRHS is INTEGER
66: *> The number of right hand sides, i.e., the number of columns
67: *> of the matrix B. NRHS >= 0.
68: *> \endverbatim
69: *>
70: *> \param[in] A
71: *> \verbatim
72: *> A is COMPLEX*16array, dimension (LDA,N)
73: *> Details of factors computed by ZHETRF_AA_2STAGE.
74: *> \endverbatim
75: *>
76: *> \param[in] LDA
77: *> \verbatim
78: *> LDA is INTEGER
79: *> The leading dimension of the array A. LDA >= max(1,N).
80: *> \endverbatim
81: *>
82: *> \param[out] TB
83: *> \verbatim
84: *> TB is COMPLEX*16array, dimension (LTB)
85: *> Details of factors computed by ZHETRF_AA_2STAGE.
86: *> \endverbatim
87: *>
88: *> \param[in] LTB
89: *> \verbatim
90: *> The size of the array TB. LTB >= 4*N.
91: *> \endverbatim
92: *>
93: *> \param[in] IPIV
94: *> \verbatim
95: *> IPIV is INTEGER array, dimension (N)
96: *> Details of the interchanges as computed by
97: *> ZHETRF_AA_2STAGE.
98: *> \endverbatim
99: *>
100: *> \param[in] IPIV2
101: *> \verbatim
102: *> IPIV2 is INTEGER array, dimension (N)
103: *> Details of the interchanges as computed by
104: *> ZHETRF_AA_2STAGE.
105: *> \endverbatim
106: *>
107: *> \param[in,out] B
108: *> \verbatim
109: *> B is COMPLEX*16array, dimension (LDB,NRHS)
110: *> On entry, the right hand side matrix B.
111: *> On exit, the solution matrix X.
112: *> \endverbatim
113: *>
114: *> \param[in] LDB
115: *> \verbatim
116: *> LDB is INTEGER
117: *> The leading dimension of the array B. LDB >= max(1,N).
118: *> \endverbatim
119: *>
120: *> \param[out] INFO
121: *> \verbatim
122: *> INFO is INTEGER
123: *> = 0: successful exit
124: *> < 0: if INFO = -i, the i-th argument had an illegal value
125: *> \endverbatim
126: *
127: * Authors:
128: * ========
129: *
130: *> \author Univ. of Tennessee
131: *> \author Univ. of California Berkeley
132: *> \author Univ. of Colorado Denver
133: *> \author NAG Ltd.
134: *
135: *> \date November 2017
136: *
137: *> \ingroup complex16SYcomputational
138: *
139: * =====================================================================
140: SUBROUTINE ZHETRS_AA_2STAGE( UPLO, N, NRHS, A, LDA, TB, LTB,
141: $ IPIV, IPIV2, B, LDB, INFO )
142: *
143: * -- LAPACK computational routine (version 3.8.0) --
144: * -- LAPACK is a software package provided by Univ. of Tennessee, --
145: * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
146: * November 2017
147: *
148: IMPLICIT NONE
149: *
150: * .. Scalar Arguments ..
151: CHARACTER UPLO
152: INTEGER N, NRHS, LDA, LTB, LDB, INFO
153: * ..
154: * .. Array Arguments ..
155: INTEGER IPIV( * ), IPIV2( * )
156: COMPLEX*16 A( LDA, * ), TB( * ), B( LDB, * )
157: * ..
158: *
159: * =====================================================================
160: *
161: COMPLEX*16 ONE
162: PARAMETER ( ONE = ( 1.0D+0, 0.0D+0 ) )
163: * ..
164: * .. Local Scalars ..
165: INTEGER LDTB, NB
166: LOGICAL UPPER
167: * ..
168: * .. External Functions ..
169: LOGICAL LSAME
170: EXTERNAL LSAME
171: * ..
172: * .. External Subroutines ..
173: EXTERNAL ZGBTRS, ZLASWP, ZTRSM, XERBLA
174: * ..
175: * .. Intrinsic Functions ..
176: INTRINSIC MAX
177: * ..
178: * .. Executable Statements ..
179: *
180: INFO = 0
181: UPPER = LSAME( UPLO, 'U' )
182: IF( .NOT.UPPER .AND. .NOT.LSAME( UPLO, 'L' ) ) THEN
183: INFO = -1
184: ELSE IF( N.LT.0 ) THEN
185: INFO = -2
186: ELSE IF( NRHS.LT.0 ) THEN
187: INFO = -3
188: ELSE IF( LDA.LT.MAX( 1, N ) ) THEN
189: INFO = -5
190: ELSE IF( LTB.LT.( 4*N ) ) THEN
191: INFO = -7
192: ELSE IF( LDB.LT.MAX( 1, N ) ) THEN
193: INFO = -11
194: END IF
195: IF( INFO.NE.0 ) THEN
196: CALL XERBLA( 'ZHETRS_AA_2STAGE', -INFO )
197: RETURN
198: END IF
199: *
200: * Quick return if possible
201: *
202: IF( N.EQ.0 .OR. NRHS.EQ.0 )
203: $ RETURN
204: *
205: * Read NB and compute LDTB
206: *
207: NB = INT( TB( 1 ) )
208: LDTB = LTB/N
209: *
210: IF( UPPER ) THEN
211: *
212: * Solve A*X = B, where A = U*T*U**T.
213: *
214: IF( N.GT.NB ) THEN
215: *
216: * Pivot, P**T * B
217: *
218: CALL ZLASWP( NRHS, B, LDB, NB+1, N, IPIV, 1 )
219: *
220: * Compute (U**T \P**T * B) -> B [ (U**T \P**T * B) ]
221: *
222: CALL ZTRSM( 'L', 'U', 'C', 'U', N-NB, NRHS, ONE, A(1, NB+1),
223: $ LDA, B(NB+1, 1), LDB)
224: *
225: END IF
226: *
227: * Compute T \ B -> B [ T \ (U**T \P**T * B) ]
228: *
229: CALL ZGBTRS( 'N', N, NB, NB, NRHS, TB, LDTB, IPIV2, B, LDB,
230: $ INFO)
231: IF( N.GT.NB ) THEN
232: *
233: * Compute (U \ B) -> B [ U \ (T \ (U**T \P**T * B) ) ]
234: *
235: CALL ZTRSM( 'L', 'U', 'N', 'U', N-NB, NRHS, ONE, A(1, NB+1),
236: $ LDA, B(NB+1, 1), LDB)
237: *
238: * Pivot, P * B [ P * (U \ (T \ (U**T \P**T * B) )) ]
239: *
240: CALL ZLASWP( NRHS, B, LDB, NB+1, N, IPIV, -1 )
241: *
242: END IF
243: *
244: ELSE
245: *
246: * Solve A*X = B, where A = L*T*L**T.
247: *
248: IF( N.GT.NB ) THEN
249: *
250: * Pivot, P**T * B
251: *
252: CALL ZLASWP( NRHS, B, LDB, NB+1, N, IPIV, 1 )
253: *
254: * Compute (L \P**T * B) -> B [ (L \P**T * B) ]
255: *
256: CALL ZTRSM( 'L', 'L', 'N', 'U', N-NB, NRHS, ONE, A(NB+1, 1),
257: $ LDA, B(NB+1, 1), LDB)
258: *
259: END IF
260: *
261: * Compute T \ B -> B [ T \ (L \P**T * B) ]
262: *
263: CALL ZGBTRS( 'N', N, NB, NB, NRHS, TB, LDTB, IPIV2, B, LDB,
264: $ INFO)
265: IF( N.GT.NB ) THEN
266: *
267: * Compute (L**T \ B) -> B [ L**T \ (T \ (L \P**T * B) ) ]
268: *
269: CALL ZTRSM( 'L', 'L', 'C', 'U', N-NB, NRHS, ONE, A(NB+1, 1),
270: $ LDA, B(NB+1, 1), LDB)
271: *
272: * Pivot, P * B [ P * (L**T \ (T \ (L \P**T * B) )) ]
273: *
274: CALL ZLASWP( NRHS, B, LDB, NB+1, N, IPIV, -1 )
275: *
276: END IF
277: END IF
278: *
279: RETURN
280: *
281: * End of ZHETRS_AA_2STAGE
282: *
283: END
CVSweb interface <joel.bertrand@systella.fr>
![[BACK]](/cvsweb/icons/back.gif){kind=icon}
Return to zhetrs_aa_2stage.f CVS log ![[TXT]](/cvsweb/icons/text.gif){kind=icon}
![[DIR]](/cvsweb/icons/dir.gif){kind=icon}
Up to [local] / rpl / lapack / lapack