Annotation of rpl/lapack/lapack/zpotri.f, revision 1.18
1.9 bertrand 1: *> \brief \b ZPOTRI
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 ZPOTRI + dependencies
10: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/zpotri.f">
11: *> [TGZ]</a>
12: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/zpotri.f">
13: *> [ZIP]</a>
14: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/zpotri.f">
1.9 bertrand 15: *> [TXT]</a>
1.15 bertrand 16: *> \endhtmlonly
1.9 bertrand 17: *
18: * Definition:
19: * ===========
20: *
21: * SUBROUTINE ZPOTRI( UPLO, N, A, LDA, INFO )
1.15 bertrand 22: *
1.9 bertrand 23: * .. Scalar Arguments ..
24: * CHARACTER UPLO
25: * INTEGER INFO, LDA, N
26: * ..
27: * .. Array Arguments ..
28: * COMPLEX*16 A( LDA, * )
29: * ..
1.15 bertrand 30: *
1.9 bertrand 31: *
32: *> \par Purpose:
33: * =============
34: *>
35: *> \verbatim
36: *>
37: *> ZPOTRI computes the inverse of a complex Hermitian positive definite
38: *> matrix A using the Cholesky factorization A = U**H*U or A = L*L**H
39: *> computed by ZPOTRF.
40: *> \endverbatim
41: *
42: * Arguments:
43: * ==========
44: *
45: *> \param[in] UPLO
46: *> \verbatim
47: *> UPLO is CHARACTER*1
48: *> = 'U': Upper triangle of A is stored;
49: *> = 'L': Lower triangle of A is stored.
50: *> \endverbatim
51: *>
52: *> \param[in] N
53: *> \verbatim
54: *> N is INTEGER
55: *> The order of the matrix A. N >= 0.
56: *> \endverbatim
57: *>
58: *> \param[in,out] A
59: *> \verbatim
60: *> A is COMPLEX*16 array, dimension (LDA,N)
61: *> On entry, the triangular factor U or L from the Cholesky
62: *> factorization A = U**H*U or A = L*L**H, as computed by
63: *> ZPOTRF.
64: *> On exit, the upper or lower triangle of the (Hermitian)
65: *> inverse of A, overwriting the input factor U or L.
66: *> \endverbatim
67: *>
68: *> \param[in] LDA
69: *> \verbatim
70: *> LDA is INTEGER
71: *> The leading dimension of the array A. LDA >= max(1,N).
72: *> \endverbatim
73: *>
74: *> \param[out] INFO
75: *> \verbatim
76: *> INFO is INTEGER
77: *> = 0: successful exit
78: *> < 0: if INFO = -i, the i-th argument had an illegal value
79: *> > 0: if INFO = i, the (i,i) element of the factor U or L is
80: *> zero, and the inverse could not be computed.
81: *> \endverbatim
82: *
83: * Authors:
84: * ========
85: *
1.15 bertrand 86: *> \author Univ. of Tennessee
87: *> \author Univ. of California Berkeley
88: *> \author Univ. of Colorado Denver
89: *> \author NAG Ltd.
1.9 bertrand 90: *
91: *> \ingroup complex16POcomputational
92: *
93: * =====================================================================
1.1 bertrand 94: SUBROUTINE ZPOTRI( UPLO, N, A, LDA, INFO )
95: *
1.18 ! bertrand 96: * -- LAPACK computational routine --
1.1 bertrand 97: * -- LAPACK is a software package provided by Univ. of Tennessee, --
98: * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
99: *
100: * .. Scalar Arguments ..
101: CHARACTER UPLO
102: INTEGER INFO, LDA, N
103: * ..
104: * .. Array Arguments ..
105: COMPLEX*16 A( LDA, * )
106: * ..
107: *
108: * =====================================================================
109: *
110: * .. External Functions ..
111: LOGICAL LSAME
112: EXTERNAL LSAME
113: * ..
114: * .. External Subroutines ..
115: EXTERNAL XERBLA, ZLAUUM, ZTRTRI
116: * ..
117: * .. Intrinsic Functions ..
118: INTRINSIC MAX
119: * ..
120: * .. Executable Statements ..
121: *
122: * Test the input parameters.
123: *
124: INFO = 0
125: IF( .NOT.LSAME( UPLO, 'U' ) .AND. .NOT.LSAME( UPLO, 'L' ) ) THEN
126: INFO = -1
127: ELSE IF( N.LT.0 ) THEN
128: INFO = -2
129: ELSE IF( LDA.LT.MAX( 1, N ) ) THEN
130: INFO = -4
131: END IF
132: IF( INFO.NE.0 ) THEN
133: CALL XERBLA( 'ZPOTRI', -INFO )
134: RETURN
135: END IF
136: *
137: * Quick return if possible
138: *
139: IF( N.EQ.0 )
140: $ RETURN
141: *
142: * Invert the triangular Cholesky factor U or L.
143: *
144: CALL ZTRTRI( UPLO, 'Non-unit', N, A, LDA, INFO )
145: IF( INFO.GT.0 )
146: $ RETURN
147: *
1.8 bertrand 148: * Form inv(U) * inv(U)**H or inv(L)**H * inv(L).
1.1 bertrand 149: *
150: CALL ZLAUUM( UPLO, N, A, LDA, INFO )
151: *
152: RETURN
153: *
154: * End of ZPOTRI
155: *
156: END
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