LAPACK 3.11.0
LAPACK: Linear Algebra PACKage
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cpotri.f
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1*> \brief \b CPOTRI
2*
3* =========== DOCUMENTATION ===========
4*
5* Online html documentation available at
6* http://www.netlib.org/lapack/explore-html/
7*
8*> \htmlonly
9*> Download CPOTRI + dependencies
10*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/cpotri.f">
11*> [TGZ]</a>
12*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/cpotri.f">
13*> [ZIP]</a>
14*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/cpotri.f">
15*> [TXT]</a>
16*> \endhtmlonly
17*
18* Definition:
19* ===========
20*
21* SUBROUTINE CPOTRI( UPLO, N, A, LDA, INFO )
22*
23* .. Scalar Arguments ..
24* CHARACTER UPLO
25* INTEGER INFO, LDA, N
26* ..
27* .. Array Arguments ..
28* COMPLEX A( LDA, * )
29* ..
30*
31*
32*> \par Purpose:
33* =============
34*>
35*> \verbatim
36*>
37*> CPOTRI 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 CPOTRF.
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 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*> CPOTRF.
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*
86*> \author Univ. of Tennessee
87*> \author Univ. of California Berkeley
88*> \author Univ. of Colorado Denver
89*> \author NAG Ltd.
90*
91*> \ingroup complexPOcomputational
92*
93* =====================================================================
94 SUBROUTINE cpotri( UPLO, N, A, LDA, INFO )
95*
96* -- LAPACK computational routine --
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 A( LDA, * )
106* ..
107*
108* =====================================================================
109*
110* .. External Functions ..
111 LOGICAL LSAME
112 EXTERNAL lsame
113* ..
114* .. External Subroutines ..
115 EXTERNAL clauum, ctrtri, xerbla
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( 'CPOTRI', -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 ctrtri( uplo, 'Non-unit', n, a, lda, info )
145 IF( info.GT.0 )
146 $ RETURN
147*
148* Form inv(U) * inv(U)**H or inv(L)**H * inv(L).
149*
150 CALL clauum( uplo, n, a, lda, info )
151*
152 RETURN
153*
154* End of CPOTRI
155*
156 END
subroutine xerbla(SRNAME, INFO)
XERBLA
Definition: xerbla.f:60
subroutine clauum(UPLO, N, A, LDA, INFO)
CLAUUM computes the product UUH or LHL, where U and L are upper or lower triangular matrices (blocked...
Definition: clauum.f:102
subroutine ctrtri(UPLO, DIAG, N, A, LDA, INFO)
CTRTRI
Definition: ctrtri.f:109
subroutine cpotri(UPLO, N, A, LDA, INFO)
CPOTRI
Definition: cpotri.f:95