LAPACK 3.12.0 LAPACK: Linear Algebra PACKage
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## ◆ cpotri()

 subroutine cpotri ( character uplo, integer n, complex, dimension( lda, * ) a, integer lda, integer info )

CPOTRI

Purpose:
``` CPOTRI computes the inverse of a complex Hermitian positive definite
matrix A using the Cholesky factorization A = U**H*U or A = L*L**H
computed by CPOTRF.```
Parameters
 [in] UPLO ``` UPLO is CHARACTER*1 = 'U': Upper triangle of A is stored; = 'L': Lower triangle of A is stored.``` [in] N ``` N is INTEGER The order of the matrix A. N >= 0.``` [in,out] A ``` A is COMPLEX array, dimension (LDA,N) On entry, the triangular factor U or L from the Cholesky factorization A = U**H*U or A = L*L**H, as computed by CPOTRF. On exit, the upper or lower triangle of the (Hermitian) inverse of A, overwriting the input factor U or L.``` [in] LDA ``` LDA is INTEGER The leading dimension of the array A. LDA >= max(1,N).``` [out] INFO ``` INFO is INTEGER = 0: successful exit < 0: if INFO = -i, the i-th argument had an illegal value > 0: if INFO = i, the (i,i) element of the factor U or L is zero, and the inverse could not be computed.```

Definition at line 94 of file cpotri.f.

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*
subroutine xerbla(srname, info)
Definition cblat2.f:3285
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
logical function lsame(ca, cb)
LSAME
Definition lsame.f:48
subroutine ctrtri(uplo, diag, n, a, lda, info)
CTRTRI
Definition ctrtri.f:109
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