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645 lines
19 KiB
645 lines
19 KiB
2 years ago
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*> \brief \b CSYTRI_3X
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*
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* =========== DOCUMENTATION ===========
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*
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* Online html documentation available at
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* http://www.netlib.org/lapack/explore-html/
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*
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*> \htmlonly
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*> Download CSYTRI_3X + dependencies
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*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/csytri_3x.f">
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*> [TGZ]</a>
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*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/csytri_3x.f">
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*> [ZIP]</a>
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*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/csytri_3x.f">
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*> [TXT]</a>
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*> \endhtmlonly
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*
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* Definition:
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* ===========
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*
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* SUBROUTINE CSYTRI_3X( UPLO, N, A, LDA, E, IPIV, WORK, NB, INFO )
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*
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* .. Scalar Arguments ..
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* CHARACTER UPLO
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* INTEGER INFO, LDA, N, NB
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* ..
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* .. Array Arguments ..
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* INTEGER IPIV( * )
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* COMPLEX*16 A( LDA, * ), E( * ), WORK( N+NB+1, * )
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* ..
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*
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*
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*> \par Purpose:
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* =============
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*>
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*> \verbatim
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*> CSYTRI_3X computes the inverse of a complex symmetric indefinite
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*> matrix A using the factorization computed by CSYTRF_RK or CSYTRF_BK:
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*>
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*> A = P*U*D*(U**T)*(P**T) or A = P*L*D*(L**T)*(P**T),
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*>
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*> where U (or L) is unit upper (or lower) triangular matrix,
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*> U**T (or L**T) is the transpose of U (or L), P is a permutation
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*> matrix, P**T is the transpose of P, and D is symmetric and block
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*> diagonal with 1-by-1 and 2-by-2 diagonal blocks.
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*>
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*> This is the blocked version of the algorithm, calling Level 3 BLAS.
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*> \endverbatim
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*
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* Arguments:
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* ==========
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*
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*> \param[in] UPLO
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*> \verbatim
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*> UPLO is CHARACTER*1
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*> Specifies whether the details of the factorization are
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*> stored as an upper or lower triangular matrix.
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*> = 'U': Upper triangle of A is stored;
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*> = 'L': Lower triangle of A is stored.
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*> \endverbatim
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*>
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*> \param[in] N
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*> \verbatim
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*> N is INTEGER
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*> The order of the matrix A. N >= 0.
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*> \endverbatim
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*>
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*> \param[in,out] A
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*> \verbatim
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*> A is COMPLEX array, dimension (LDA,N)
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*> On entry, diagonal of the block diagonal matrix D and
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*> factors U or L as computed by CSYTRF_RK and CSYTRF_BK:
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*> a) ONLY diagonal elements of the symmetric block diagonal
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*> matrix D on the diagonal of A, i.e. D(k,k) = A(k,k);
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*> (superdiagonal (or subdiagonal) elements of D
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*> should be provided on entry in array E), and
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*> b) If UPLO = 'U': factor U in the superdiagonal part of A.
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*> If UPLO = 'L': factor L in the subdiagonal part of A.
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*>
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*> On exit, if INFO = 0, the symmetric inverse of the original
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*> matrix.
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*> If UPLO = 'U': the upper triangular part of the inverse
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*> is formed and the part of A below the diagonal is not
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*> referenced;
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*> If UPLO = 'L': the lower triangular part of the inverse
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*> is formed and the part of A above the diagonal is not
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*> referenced.
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*> \endverbatim
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*>
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*> \param[in] LDA
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*> \verbatim
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*> LDA is INTEGER
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*> The leading dimension of the array A. LDA >= max(1,N).
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*> \endverbatim
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*>
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*> \param[in] E
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*> \verbatim
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*> E is COMPLEX array, dimension (N)
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*> On entry, contains the superdiagonal (or subdiagonal)
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*> elements of the symmetric block diagonal matrix D
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*> with 1-by-1 or 2-by-2 diagonal blocks, where
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*> If UPLO = 'U': E(i) = D(i-1,i), i=2:N, E(1) not referenced;
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*> If UPLO = 'L': E(i) = D(i+1,i), i=1:N-1, E(N) not referenced.
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*>
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*> NOTE: For 1-by-1 diagonal block D(k), where
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*> 1 <= k <= N, the element E(k) is not referenced in both
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*> UPLO = 'U' or UPLO = 'L' cases.
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*> \endverbatim
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*>
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*> \param[in] IPIV
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*> \verbatim
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*> IPIV is INTEGER array, dimension (N)
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*> Details of the interchanges and the block structure of D
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*> as determined by CSYTRF_RK or CSYTRF_BK.
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*> \endverbatim
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*>
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*> \param[out] WORK
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*> \verbatim
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*> WORK is COMPLEX array, dimension (N+NB+1,NB+3).
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*> \endverbatim
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*>
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*> \param[in] NB
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*> \verbatim
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*> NB is INTEGER
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*> Block size.
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*> \endverbatim
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*>
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*> \param[out] INFO
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*> \verbatim
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*> INFO is INTEGER
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*> = 0: successful exit
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*> < 0: if INFO = -i, the i-th argument had an illegal value
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*> > 0: if INFO = i, D(i,i) = 0; the matrix is singular and its
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*> inverse could not be computed.
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*> \endverbatim
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*
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* Authors:
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* ========
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*
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*> \author Univ. of Tennessee
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*> \author Univ. of California Berkeley
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*> \author Univ. of Colorado Denver
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*> \author NAG Ltd.
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*
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*> \ingroup complexSYcomputational
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*
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*> \par Contributors:
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* ==================
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*> \verbatim
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*>
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*> June 2017, Igor Kozachenko,
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*> Computer Science Division,
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*> University of California, Berkeley
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*>
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*> \endverbatim
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*
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* =====================================================================
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SUBROUTINE CSYTRI_3X( UPLO, N, A, LDA, E, IPIV, WORK, NB, INFO )
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*
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* -- LAPACK computational routine --
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* -- LAPACK is a software package provided by Univ. of Tennessee, --
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* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
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*
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* .. Scalar Arguments ..
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CHARACTER UPLO
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INTEGER INFO, LDA, N, NB
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* ..
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* .. Array Arguments ..
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INTEGER IPIV( * )
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COMPLEX A( LDA, * ), E( * ), WORK( N+NB+1, * )
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* ..
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*
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* =====================================================================
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*
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* .. Parameters ..
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COMPLEX CONE, CZERO
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PARAMETER ( CONE = ( 1.0E+0, 0.0E+0 ),
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$ CZERO = ( 0.0E+0, 0.0E+0 ) )
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* ..
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* .. Local Scalars ..
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LOGICAL UPPER
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INTEGER CUT, I, ICOUNT, INVD, IP, K, NNB, J, U11
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COMPLEX AK, AKKP1, AKP1, D, T, U01_I_J, U01_IP1_J,
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$ U11_I_J, U11_IP1_J
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* ..
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* .. External Functions ..
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LOGICAL LSAME
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EXTERNAL LSAME
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* ..
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* .. External Subroutines ..
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EXTERNAL CGEMM, CSYSWAPR, CTRTRI, CTRMM, XERBLA
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* ..
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* .. Intrinsic Functions ..
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INTRINSIC ABS, MAX, MOD
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* ..
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* .. Executable Statements ..
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*
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* Test the input parameters.
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*
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INFO = 0
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UPPER = LSAME( UPLO, 'U' )
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IF( .NOT.UPPER .AND. .NOT.LSAME( UPLO, 'L' ) ) THEN
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INFO = -1
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ELSE IF( N.LT.0 ) THEN
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INFO = -2
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ELSE IF( LDA.LT.MAX( 1, N ) ) THEN
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INFO = -4
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END IF
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*
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* Quick return if possible
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*
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IF( INFO.NE.0 ) THEN
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CALL XERBLA( 'CSYTRI_3X', -INFO )
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RETURN
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END IF
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IF( N.EQ.0 )
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$ RETURN
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*
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* Workspace got Non-diag elements of D
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*
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DO K = 1, N
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WORK( K, 1 ) = E( K )
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END DO
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*
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* Check that the diagonal matrix D is nonsingular.
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*
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IF( UPPER ) THEN
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*
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* Upper triangular storage: examine D from bottom to top
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*
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DO INFO = N, 1, -1
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IF( IPIV( INFO ).GT.0 .AND. A( INFO, INFO ).EQ.CZERO )
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$ RETURN
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END DO
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ELSE
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*
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* Lower triangular storage: examine D from top to bottom.
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*
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DO INFO = 1, N
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IF( IPIV( INFO ).GT.0 .AND. A( INFO, INFO ).EQ.CZERO )
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$ RETURN
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END DO
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END IF
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*
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INFO = 0
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*
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* Splitting Workspace
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* U01 is a block ( N, NB+1 )
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* The first element of U01 is in WORK( 1, 1 )
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* U11 is a block ( NB+1, NB+1 )
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* The first element of U11 is in WORK( N+1, 1 )
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*
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U11 = N
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*
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* INVD is a block ( N, 2 )
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* The first element of INVD is in WORK( 1, INVD )
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*
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INVD = NB + 2
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IF( UPPER ) THEN
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*
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* Begin Upper
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*
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* invA = P * inv(U**T) * inv(D) * inv(U) * P**T.
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*
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CALL CTRTRI( UPLO, 'U', N, A, LDA, INFO )
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*
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* inv(D) and inv(D) * inv(U)
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*
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K = 1
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DO WHILE( K.LE.N )
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IF( IPIV( K ).GT.0 ) THEN
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* 1 x 1 diagonal NNB
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WORK( K, INVD ) = CONE / A( K, K )
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WORK( K, INVD+1 ) = CZERO
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ELSE
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* 2 x 2 diagonal NNB
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T = WORK( K+1, 1 )
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AK = A( K, K ) / T
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AKP1 = A( K+1, K+1 ) / T
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AKKP1 = WORK( K+1, 1 ) / T
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D = T*( AK*AKP1-CONE )
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WORK( K, INVD ) = AKP1 / D
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WORK( K+1, INVD+1 ) = AK / D
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WORK( K, INVD+1 ) = -AKKP1 / D
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WORK( K+1, INVD ) = WORK( K, INVD+1 )
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K = K + 1
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END IF
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K = K + 1
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END DO
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*
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* inv(U**T) = (inv(U))**T
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*
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* inv(U**T) * inv(D) * inv(U)
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*
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CUT = N
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DO WHILE( CUT.GT.0 )
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NNB = NB
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IF( CUT.LE.NNB ) THEN
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NNB = CUT
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ELSE
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ICOUNT = 0
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* count negative elements,
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DO I = CUT+1-NNB, CUT
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IF( IPIV( I ).LT.0 ) ICOUNT = ICOUNT + 1
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END DO
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* need a even number for a clear cut
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IF( MOD( ICOUNT, 2 ).EQ.1 ) NNB = NNB + 1
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END IF
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CUT = CUT - NNB
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*
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* U01 Block
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*
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DO I = 1, CUT
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DO J = 1, NNB
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WORK( I, J ) = A( I, CUT+J )
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END DO
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END DO
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*
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* U11 Block
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*
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DO I = 1, NNB
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WORK( U11+I, I ) = CONE
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DO J = 1, I-1
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WORK( U11+I, J ) = CZERO
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END DO
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DO J = I+1, NNB
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WORK( U11+I, J ) = A( CUT+I, CUT+J )
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END DO
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END DO
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*
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* invD * U01
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*
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I = 1
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DO WHILE( I.LE.CUT )
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IF( IPIV( I ).GT.0 ) THEN
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DO J = 1, NNB
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WORK( I, J ) = WORK( I, INVD ) * WORK( I, J )
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END DO
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ELSE
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DO J = 1, NNB
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U01_I_J = WORK( I, J )
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U01_IP1_J = WORK( I+1, J )
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WORK( I, J ) = WORK( I, INVD ) * U01_I_J
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$ + WORK( I, INVD+1 ) * U01_IP1_J
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WORK( I+1, J ) = WORK( I+1, INVD ) * U01_I_J
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$ + WORK( I+1, INVD+1 ) * U01_IP1_J
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END DO
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I = I + 1
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END IF
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I = I + 1
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END DO
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*
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* invD1 * U11
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*
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I = 1
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DO WHILE ( I.LE.NNB )
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IF( IPIV( CUT+I ).GT.0 ) THEN
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DO J = I, NNB
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WORK( U11+I, J ) = WORK(CUT+I,INVD) * WORK(U11+I,J)
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END DO
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ELSE
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DO J = I, NNB
|
||
|
|
U11_I_J = WORK(U11+I,J)
|
||
|
|
U11_IP1_J = WORK(U11+I+1,J)
|
||
|
|
WORK( U11+I, J ) = WORK(CUT+I,INVD) * WORK(U11+I,J)
|
||
|
|
$ + WORK(CUT+I,INVD+1) * WORK(U11+I+1,J)
|
||
|
|
WORK( U11+I+1, J ) = WORK(CUT+I+1,INVD) * U11_I_J
|
||
|
|
$ + WORK(CUT+I+1,INVD+1) * U11_IP1_J
|
||
|
|
END DO
|
||
|
|
I = I + 1
|
||
|
|
END IF
|
||
|
|
I = I + 1
|
||
|
|
END DO
|
||
|
|
*
|
||
|
|
* U11**T * invD1 * U11 -> U11
|
||
|
|
*
|
||
|
|
CALL CTRMM( 'L', 'U', 'T', 'U', NNB, NNB,
|
||
|
|
$ CONE, A( CUT+1, CUT+1 ), LDA, WORK( U11+1, 1 ),
|
||
|
|
$ N+NB+1 )
|
||
|
|
*
|
||
|
|
DO I = 1, NNB
|
||
|
|
DO J = I, NNB
|
||
|
|
A( CUT+I, CUT+J ) = WORK( U11+I, J )
|
||
|
|
END DO
|
||
|
|
END DO
|
||
|
|
*
|
||
|
|
* U01**T * invD * U01 -> A( CUT+I, CUT+J )
|
||
|
|
*
|
||
|
|
CALL CGEMM( 'T', 'N', NNB, NNB, CUT, CONE, A( 1, CUT+1 ),
|
||
|
|
$ LDA, WORK, N+NB+1, CZERO, WORK(U11+1,1),
|
||
|
|
$ N+NB+1 )
|
||
|
|
|
||
|
|
*
|
||
|
|
* U11 = U11**T * invD1 * U11 + U01**T * invD * U01
|
||
|
|
*
|
||
|
|
DO I = 1, NNB
|
||
|
|
DO J = I, NNB
|
||
|
|
A( CUT+I, CUT+J ) = A( CUT+I, CUT+J ) + WORK(U11+I,J)
|
||
|
|
END DO
|
||
|
|
END DO
|
||
|
|
*
|
||
|
|
* U01 = U00**T * invD0 * U01
|
||
|
|
*
|
||
|
|
CALL CTRMM( 'L', UPLO, 'T', 'U', CUT, NNB,
|
||
|
|
$ CONE, A, LDA, WORK, N+NB+1 )
|
||
|
|
|
||
|
|
*
|
||
|
|
* Update U01
|
||
|
|
*
|
||
|
|
DO I = 1, CUT
|
||
|
|
DO J = 1, NNB
|
||
|
|
A( I, CUT+J ) = WORK( I, J )
|
||
|
|
END DO
|
||
|
|
END DO
|
||
|
|
*
|
||
|
|
* Next Block
|
||
|
|
*
|
||
|
|
END DO
|
||
|
|
*
|
||
|
|
* Apply PERMUTATIONS P and P**T:
|
||
|
|
* P * inv(U**T) * inv(D) * inv(U) * P**T.
|
||
|
|
* Interchange rows and columns I and IPIV(I) in reverse order
|
||
|
|
* from the formation order of IPIV vector for Upper case.
|
||
|
|
*
|
||
|
|
* ( We can use a loop over IPIV with increment 1,
|
||
|
|
* since the ABS value of IPIV(I) represents the row (column)
|
||
|
|
* index of the interchange with row (column) i in both 1x1
|
||
|
|
* and 2x2 pivot cases, i.e. we don't need separate code branches
|
||
|
|
* for 1x1 and 2x2 pivot cases )
|
||
|
|
*
|
||
|
|
DO I = 1, N
|
||
|
|
IP = ABS( IPIV( I ) )
|
||
|
|
IF( IP.NE.I ) THEN
|
||
|
|
IF (I .LT. IP) CALL CSYSWAPR( UPLO, N, A, LDA, I ,IP )
|
||
|
|
IF (I .GT. IP) CALL CSYSWAPR( UPLO, N, A, LDA, IP ,I )
|
||
|
|
END IF
|
||
|
|
END DO
|
||
|
|
*
|
||
|
|
ELSE
|
||
|
|
*
|
||
|
|
* Begin Lower
|
||
|
|
*
|
||
|
|
* inv A = P * inv(L**T) * inv(D) * inv(L) * P**T.
|
||
|
|
*
|
||
|
|
CALL CTRTRI( UPLO, 'U', N, A, LDA, INFO )
|
||
|
|
*
|
||
|
|
* inv(D) and inv(D) * inv(L)
|
||
|
|
*
|
||
|
|
K = N
|
||
|
|
DO WHILE ( K .GE. 1 )
|
||
|
|
IF( IPIV( K ).GT.0 ) THEN
|
||
|
|
* 1 x 1 diagonal NNB
|
||
|
|
WORK( K, INVD ) = CONE / A( K, K )
|
||
|
|
WORK( K, INVD+1 ) = CZERO
|
||
|
|
ELSE
|
||
|
|
* 2 x 2 diagonal NNB
|
||
|
|
T = WORK( K-1, 1 )
|
||
|
|
AK = A( K-1, K-1 ) / T
|
||
|
|
AKP1 = A( K, K ) / T
|
||
|
|
AKKP1 = WORK( K-1, 1 ) / T
|
||
|
|
D = T*( AK*AKP1-CONE )
|
||
|
|
WORK( K-1, INVD ) = AKP1 / D
|
||
|
|
WORK( K, INVD ) = AK / D
|
||
|
|
WORK( K, INVD+1 ) = -AKKP1 / D
|
||
|
|
WORK( K-1, INVD+1 ) = WORK( K, INVD+1 )
|
||
|
|
K = K - 1
|
||
|
|
END IF
|
||
|
|
K = K - 1
|
||
|
|
END DO
|
||
|
|
*
|
||
|
|
* inv(L**T) = (inv(L))**T
|
||
|
|
*
|
||
|
|
* inv(L**T) * inv(D) * inv(L)
|
||
|
|
*
|
||
|
|
CUT = 0
|
||
|
|
DO WHILE( CUT.LT.N )
|
||
|
|
NNB = NB
|
||
|
|
IF( (CUT + NNB).GT.N ) THEN
|
||
|
|
NNB = N - CUT
|
||
|
|
ELSE
|
||
|
|
ICOUNT = 0
|
||
|
|
* count negative elements,
|
||
|
|
DO I = CUT + 1, CUT+NNB
|
||
|
|
IF ( IPIV( I ).LT.0 ) ICOUNT = ICOUNT + 1
|
||
|
|
END DO
|
||
|
|
* need a even number for a clear cut
|
||
|
|
IF( MOD( ICOUNT, 2 ).EQ.1 ) NNB = NNB + 1
|
||
|
|
END IF
|
||
|
|
*
|
||
|
|
* L21 Block
|
||
|
|
*
|
||
|
|
DO I = 1, N-CUT-NNB
|
||
|
|
DO J = 1, NNB
|
||
|
|
WORK( I, J ) = A( CUT+NNB+I, CUT+J )
|
||
|
|
END DO
|
||
|
|
END DO
|
||
|
|
*
|
||
|
|
* L11 Block
|
||
|
|
*
|
||
|
|
DO I = 1, NNB
|
||
|
|
WORK( U11+I, I) = CONE
|
||
|
|
DO J = I+1, NNB
|
||
|
|
WORK( U11+I, J ) = CZERO
|
||
|
|
END DO
|
||
|
|
DO J = 1, I-1
|
||
|
|
WORK( U11+I, J ) = A( CUT+I, CUT+J )
|
||
|
|
END DO
|
||
|
|
END DO
|
||
|
|
*
|
||
|
|
* invD*L21
|
||
|
|
*
|
||
|
|
I = N-CUT-NNB
|
||
|
|
DO WHILE( I.GE.1 )
|
||
|
|
IF( IPIV( CUT+NNB+I ).GT.0 ) THEN
|
||
|
|
DO J = 1, NNB
|
||
|
|
WORK( I, J ) = WORK( CUT+NNB+I, INVD) * WORK( I, J)
|
||
|
|
END DO
|
||
|
|
ELSE
|
||
|
|
DO J = 1, NNB
|
||
|
|
U01_I_J = WORK(I,J)
|
||
|
|
U01_IP1_J = WORK(I-1,J)
|
||
|
|
WORK(I,J)=WORK(CUT+NNB+I,INVD)*U01_I_J+
|
||
|
|
$ WORK(CUT+NNB+I,INVD+1)*U01_IP1_J
|
||
|
|
WORK(I-1,J)=WORK(CUT+NNB+I-1,INVD+1)*U01_I_J+
|
||
|
|
$ WORK(CUT+NNB+I-1,INVD)*U01_IP1_J
|
||
|
|
END DO
|
||
|
|
I = I - 1
|
||
|
|
END IF
|
||
|
|
I = I - 1
|
||
|
|
END DO
|
||
|
|
*
|
||
|
|
* invD1*L11
|
||
|
|
*
|
||
|
|
I = NNB
|
||
|
|
DO WHILE( I.GE.1 )
|
||
|
|
IF( IPIV( CUT+I ).GT.0 ) THEN
|
||
|
|
DO J = 1, NNB
|
||
|
|
WORK( U11+I, J ) = WORK( CUT+I, INVD)*WORK(U11+I,J)
|
||
|
|
END DO
|
||
|
|
|
||
|
|
ELSE
|
||
|
|
DO J = 1, NNB
|
||
|
|
U11_I_J = WORK( U11+I, J )
|
||
|
|
U11_IP1_J = WORK( U11+I-1, J )
|
||
|
|
WORK( U11+I, J ) = WORK(CUT+I,INVD) * WORK(U11+I,J)
|
||
|
|
$ + WORK(CUT+I,INVD+1) * U11_IP1_J
|
||
|
|
WORK( U11+I-1, J ) = WORK(CUT+I-1,INVD+1) * U11_I_J
|
||
|
|
$ + WORK(CUT+I-1,INVD) * U11_IP1_J
|
||
|
|
END DO
|
||
|
|
I = I - 1
|
||
|
|
END IF
|
||
|
|
I = I - 1
|
||
|
|
END DO
|
||
|
|
*
|
||
|
|
* L11**T * invD1 * L11 -> L11
|
||
|
|
*
|
||
|
|
CALL CTRMM( 'L', UPLO, 'T', 'U', NNB, NNB, CONE,
|
||
|
|
$ A( CUT+1, CUT+1 ), LDA, WORK( U11+1, 1 ),
|
||
|
|
$ N+NB+1 )
|
||
|
|
|
||
|
|
*
|
||
|
|
DO I = 1, NNB
|
||
|
|
DO J = 1, I
|
||
|
|
A( CUT+I, CUT+J ) = WORK( U11+I, J )
|
||
|
|
END DO
|
||
|
|
END DO
|
||
|
|
*
|
||
|
|
IF( (CUT+NNB).LT.N ) THEN
|
||
|
|
*
|
||
|
|
* L21**T * invD2*L21 -> A( CUT+I, CUT+J )
|
||
|
|
*
|
||
|
|
CALL CGEMM( 'T', 'N', NNB, NNB, N-NNB-CUT, CONE,
|
||
|
|
$ A( CUT+NNB+1, CUT+1 ), LDA, WORK, N+NB+1,
|
||
|
|
$ CZERO, WORK( U11+1, 1 ), N+NB+1 )
|
||
|
|
|
||
|
|
*
|
||
|
|
* L11 = L11**T * invD1 * L11 + U01**T * invD * U01
|
||
|
|
*
|
||
|
|
DO I = 1, NNB
|
||
|
|
DO J = 1, I
|
||
|
|
A( CUT+I, CUT+J ) = A( CUT+I, CUT+J )+WORK(U11+I,J)
|
||
|
|
END DO
|
||
|
|
END DO
|
||
|
|
*
|
||
|
|
* L01 = L22**T * invD2 * L21
|
||
|
|
*
|
||
|
|
CALL CTRMM( 'L', UPLO, 'T', 'U', N-NNB-CUT, NNB, CONE,
|
||
|
|
$ A( CUT+NNB+1, CUT+NNB+1 ), LDA, WORK,
|
||
|
|
$ N+NB+1 )
|
||
|
|
*
|
||
|
|
* Update L21
|
||
|
|
*
|
||
|
|
DO I = 1, N-CUT-NNB
|
||
|
|
DO J = 1, NNB
|
||
|
|
A( CUT+NNB+I, CUT+J ) = WORK( I, J )
|
||
|
|
END DO
|
||
|
|
END DO
|
||
|
|
*
|
||
|
|
ELSE
|
||
|
|
*
|
||
|
|
* L11 = L11**T * invD1 * L11
|
||
|
|
*
|
||
|
|
DO I = 1, NNB
|
||
|
|
DO J = 1, I
|
||
|
|
A( CUT+I, CUT+J ) = WORK( U11+I, J )
|
||
|
|
END DO
|
||
|
|
END DO
|
||
|
|
END IF
|
||
|
|
*
|
||
|
|
* Next Block
|
||
|
|
*
|
||
|
|
CUT = CUT + NNB
|
||
|
|
*
|
||
|
|
END DO
|
||
|
|
*
|
||
|
|
* Apply PERMUTATIONS P and P**T:
|
||
|
|
* P * inv(L**T) * inv(D) * inv(L) * P**T.
|
||
|
|
* Interchange rows and columns I and IPIV(I) in reverse order
|
||
|
|
* from the formation order of IPIV vector for Lower case.
|
||
|
|
*
|
||
|
|
* ( We can use a loop over IPIV with increment -1,
|
||
|
|
* since the ABS value of IPIV(I) represents the row (column)
|
||
|
|
* index of the interchange with row (column) i in both 1x1
|
||
|
|
* and 2x2 pivot cases, i.e. we don't need separate code branches
|
||
|
|
* for 1x1 and 2x2 pivot cases )
|
||
|
|
*
|
||
|
|
DO I = N, 1, -1
|
||
|
|
IP = ABS( IPIV( I ) )
|
||
|
|
IF( IP.NE.I ) THEN
|
||
|
|
IF (I .LT. IP) CALL CSYSWAPR( UPLO, N, A, LDA, I ,IP )
|
||
|
|
IF (I .GT. IP) CALL CSYSWAPR( UPLO, N, A, LDA, IP ,I )
|
||
|
|
END IF
|
||
|
|
END DO
|
||
|
|
*
|
||
|
|
END IF
|
||
|
|
*
|
||
|
|
RETURN
|
||
|
|
*
|
||
|
|
* End of CSYTRI_3X
|
||
|
|
*
|
||
|
|
END
|
||
|
|
|