Annotation of rpl/lapack/lapack/zhetri2.f, revision 1.13
1.2 bertrand 1: *> \brief \b ZHETRI2
2: *
3: * =========== DOCUMENTATION ===========
4: *
1.9 bertrand 5: * Online html documentation available at
6: * http://www.netlib.org/lapack/explore-html/
1.2 bertrand 7: *
8: *> \htmlonly
1.9 bertrand 9: *> Download ZHETRI2 + dependencies
10: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/zhetri2.f">
11: *> [TGZ]</a>
12: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/zhetri2.f">
13: *> [ZIP]</a>
14: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/zhetri2.f">
1.2 bertrand 15: *> [TXT]</a>
1.9 bertrand 16: *> \endhtmlonly
1.2 bertrand 17: *
18: * Definition:
19: * ===========
20: *
21: * SUBROUTINE ZHETRI2( UPLO, N, A, LDA, IPIV, WORK, LWORK, INFO )
1.9 bertrand 22: *
1.2 bertrand 23: * .. Scalar Arguments ..
24: * CHARACTER UPLO
25: * INTEGER INFO, LDA, LWORK, N
26: * ..
27: * .. Array Arguments ..
28: * INTEGER IPIV( * )
29: * COMPLEX*16 A( LDA, * ), WORK( * )
30: * ..
1.9 bertrand 31: *
1.2 bertrand 32: *
33: *> \par Purpose:
34: * =============
35: *>
36: *> \verbatim
37: *>
38: *> ZHETRI2 computes the inverse of a COMPLEX*16 hermitian indefinite matrix
39: *> A using the factorization A = U*D*U**T or A = L*D*L**T computed by
40: *> ZHETRF. ZHETRI2 set the LEADING DIMENSION of the workspace
41: *> before calling ZHETRI2X that actually computes the inverse.
42: *> \endverbatim
43: *
44: * Arguments:
45: * ==========
46: *
47: *> \param[in] UPLO
48: *> \verbatim
49: *> UPLO is CHARACTER*1
50: *> Specifies whether the details of the factorization are stored
51: *> as an upper or lower triangular matrix.
52: *> = 'U': Upper triangular, form is A = U*D*U**T;
53: *> = 'L': Lower triangular, form is A = L*D*L**T.
54: *> \endverbatim
55: *>
56: *> \param[in] N
57: *> \verbatim
58: *> N is INTEGER
59: *> The order of the matrix A. N >= 0.
60: *> \endverbatim
61: *>
62: *> \param[in,out] A
63: *> \verbatim
64: *> A is COMPLEX*16 array, dimension (LDA,N)
1.13 ! bertrand 65: *> On entry, the block diagonal matrix D and the multipliers
1.2 bertrand 66: *> used to obtain the factor U or L as computed by ZHETRF.
67: *>
68: *> On exit, if INFO = 0, the (symmetric) inverse of the original
69: *> matrix. If UPLO = 'U', the upper triangular part of the
70: *> inverse is formed and the part of A below the diagonal is not
71: *> referenced; if UPLO = 'L' the lower triangular part of the
72: *> inverse is formed and the part of A above the diagonal is
73: *> not referenced.
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[in] IPIV
83: *> \verbatim
84: *> IPIV is INTEGER array, dimension (N)
1.13 ! bertrand 85: *> Details of the interchanges and the block structure of D
1.2 bertrand 86: *> as determined by ZHETRF.
87: *> \endverbatim
88: *>
89: *> \param[out] WORK
90: *> \verbatim
91: *> WORK is COMPLEX*16 array, dimension (N+NB+1)*(NB+3)
92: *> \endverbatim
93: *>
94: *> \param[in] LWORK
95: *> \verbatim
96: *> LWORK is INTEGER
97: *> The dimension of the array WORK.
98: *> WORK is size >= (N+NB+1)*(NB+3)
1.7 bertrand 99: *> If LWORK = -1, then a workspace query is assumed; the routine
1.2 bertrand 100: *> calculates:
101: *> - the optimal size of the WORK array, returns
102: *> this value as the first entry of the WORK array,
1.7 bertrand 103: *> - and no error message related to LWORK is issued by XERBLA.
1.2 bertrand 104: *> \endverbatim
105: *>
106: *> \param[out] INFO
107: *> \verbatim
108: *> INFO is INTEGER
109: *> = 0: successful exit
110: *> < 0: if INFO = -i, the i-th argument had an illegal value
111: *> > 0: if INFO = i, D(i,i) = 0; the matrix is singular and its
112: *> inverse could not be computed.
113: *> \endverbatim
114: *
115: * Authors:
116: * ========
117: *
1.9 bertrand 118: *> \author Univ. of Tennessee
119: *> \author Univ. of California Berkeley
120: *> \author Univ. of Colorado Denver
121: *> \author NAG Ltd.
1.2 bertrand 122: *
1.11 bertrand 123: *> \date November 2017
1.2 bertrand 124: *
125: *> \ingroup complex16HEcomputational
126: *
127: * =====================================================================
1.1 bertrand 128: SUBROUTINE ZHETRI2( UPLO, N, A, LDA, IPIV, WORK, LWORK, INFO )
129: *
1.11 bertrand 130: * -- LAPACK computational routine (version 3.8.0) --
1.1 bertrand 131: * -- LAPACK is a software package provided by Univ. of Tennessee, --
132: * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
1.11 bertrand 133: * November 2017
1.1 bertrand 134: *
135: * .. Scalar Arguments ..
136: CHARACTER UPLO
137: INTEGER INFO, LDA, LWORK, N
138: * ..
139: * .. Array Arguments ..
140: INTEGER IPIV( * )
141: COMPLEX*16 A( LDA, * ), WORK( * )
142: * ..
143: *
144: * =====================================================================
145: *
146: * .. Local Scalars ..
147: LOGICAL UPPER, LQUERY
148: INTEGER MINSIZE, NBMAX
149: * ..
150: * .. External Functions ..
151: LOGICAL LSAME
152: INTEGER ILAENV
153: EXTERNAL LSAME, ILAENV
154: * ..
155: * .. External Subroutines ..
1.11 bertrand 156: EXTERNAL ZHETRI2X, ZHETRI, XERBLA
1.1 bertrand 157: * ..
158: * .. Executable Statements ..
159: *
160: * Test the input parameters.
161: *
162: INFO = 0
163: UPPER = LSAME( UPLO, 'U' )
164: LQUERY = ( LWORK.EQ.-1 )
165: * Get blocksize
166: NBMAX = ILAENV( 1, 'ZHETRF', UPLO, N, -1, -1, -1 )
167: IF ( NBMAX .GE. N ) THEN
168: MINSIZE = N
169: ELSE
170: MINSIZE = (N+NBMAX+1)*(NBMAX+3)
171: END IF
172: *
173: IF( .NOT.UPPER .AND. .NOT.LSAME( UPLO, 'L' ) ) THEN
174: INFO = -1
175: ELSE IF( N.LT.0 ) THEN
176: INFO = -2
177: ELSE IF( LDA.LT.MAX( 1, N ) ) THEN
178: INFO = -4
179: ELSE IF (LWORK .LT. MINSIZE .AND. .NOT.LQUERY ) THEN
180: INFO = -7
181: END IF
182: *
183: * Quick return if possible
184: *
185: *
186: IF( INFO.NE.0 ) THEN
187: CALL XERBLA( 'ZHETRI2', -INFO )
188: RETURN
189: ELSE IF( LQUERY ) THEN
190: WORK(1)=MINSIZE
191: RETURN
192: END IF
193: IF( N.EQ.0 )
194: $ RETURN
1.9 bertrand 195:
1.1 bertrand 196: IF( NBMAX .GE. N ) THEN
197: CALL ZHETRI( UPLO, N, A, LDA, IPIV, WORK, INFO )
198: ELSE
199: CALL ZHETRI2X( UPLO, N, A, LDA, IPIV, WORK, NBMAX, INFO )
200: END IF
201: RETURN
202: *
203: * End of ZHETRI2
204: *
205: END
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