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diff --git a/SRC/ssytri_3.f b/SRC/ssytri_3.f new file mode 100644 index 00000000..4acad458 --- /dev/null +++ b/SRC/ssytri_3.f @@ -0,0 +1,248 @@ +*> \brief \b SSYTRI_3 +* +* =========== DOCUMENTATION =========== +* +* Online html documentation available at +* http://www.netlib.org/lapack/explore-html/ +* +*> \htmlonly +*> Download SSYTRI_3 + dependencies +*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/ssytri_3.f"> +*> [TGZ]</a> +*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/ssytri_3.f"> +*> [ZIP]</a> +*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/ssytri_3.f"> +*> [TXT]</a> +*> \endhtmlonly +* +* Definition: +* =========== +* +* SUBROUTINE SSYTRI_3( UPLO, N, A, LDA, E, IPIV, WORK, LWORK, +* INFO ) +* +* .. Scalar Arguments .. +* CHARACTER UPLO +* INTEGER INFO, LDA, LWORK, N +* .. +* .. Array Arguments .. +* INTEGER IPIV( * ) +* REAL A( LDA, * ), E( * ), WORK( * ) +* .. +* +* +*> \par Purpose: +* ============= +*> +*> \verbatim +*> SSYTRI_3 computes the inverse of a real symmetric indefinite +*> matrix A using the factorization computed by SSYTRF_RK or SSYTRF_BK: +*> +*> A = P*U*D*(U**T)*(P**T) or A = P*L*D*(L**T)*(P**T), +*> +*> where U (or L) is unit upper (or lower) triangular matrix, +*> U**T (or L**T) is the transpose of U (or L), P is a permutation +*> matrix, P**T is the transpose of P, and D is symmetric and block +*> diagonal with 1-by-1 and 2-by-2 diagonal blocks. +*> +*> SSYTRI_3 sets the leading dimension of the workspace before calling +*> SSYTRI_3X that actually computes the inverse. This is the blocked +*> version of the algorithm, calling Level 3 BLAS. +*> \endverbatim +* +* Arguments: +* ========== +* +*> \param[in] UPLO +*> \verbatim +*> UPLO is CHARACTER*1 +*> Specifies whether the details of the factorization are +*> stored as an upper or lower triangular matrix. +*> = 'U': Upper triangle of A is stored; +*> = 'L': Lower triangle of A is stored. +*> \endverbatim +*> +*> \param[in] N +*> \verbatim +*> N is INTEGER +*> The order of the matrix A. N >= 0. +*> \endverbatim +*> +*> \param[in,out] A +*> \verbatim +*> A is REAL array, dimension (LDA,N) +*> On entry, diagonal of the block diagonal matrix D and +*> factors U or L as computed by SSYTRF_RK and SSYTRF_BK: +*> a) ONLY diagonal elements of the symmetric block diagonal +*> matrix D on the diagonal of A, i.e. D(k,k) = A(k,k); +*> (superdiagonal (or subdiagonal) elements of D +*> should be provided on entry in array E), and +*> b) If UPLO = 'U': factor U in the superdiagonal part of A. +*> If UPLO = 'L': factor L in the subdiagonal part of A. +*> +*> On exit, if INFO = 0, the symmetric inverse of the original +*> matrix. +*> If UPLO = 'U': the upper triangular part of the inverse +*> is formed and the part of A below the diagonal is not +*> referenced; +*> If UPLO = 'L': the lower triangular part of the inverse +*> is formed and the part of A above the diagonal is not +*> referenced. +*> \endverbatim +*> +*> \param[in] LDA +*> \verbatim +*> LDA is INTEGER +*> The leading dimension of the array A. LDA >= max(1,N). +*> \endverbatim +*> +*> \param[in] E +*> \verbatim +*> E is REAL array, dimension (N) +*> On entry, contains the superdiagonal (or subdiagonal) +*> elements of the symmetric block diagonal matrix D +*> with 1-by-1 or 2-by-2 diagonal blocks, where +*> If UPLO = 'U': E(i) = D(i-1,i),i=2:N, E(1) not refernced; +*> If UPLO = 'L': E(i) = D(i+1,i),i=1:N-1, E(N) not referenced. +*> +*> NOTE: For 1-by-1 diagonal block D(k), where +*> 1 <= k <= N, the element E(k) is not referenced in both +*> UPLO = 'U' or UPLO = 'L' cases. +*> \endverbatim +*> +*> \param[in] IPIV +*> \verbatim +*> IPIV is INTEGER array, dimension (N) +*> Details of the interchanges and the block structure of D +*> as determined by SSYTRF_RK or SSYTRF_BK. +*> \endverbatim +*> +*> \param[out] WORK +*> \verbatim +*> WORK is REAL array, dimension (N+NB+1)*(NB+3). +*> On exit, if INFO = 0, WORK(1) returns the optimal LWORK. +*> \endverbatim +*> +*> \param[in] LWORK +*> \verbatim +*> LWORK is INTEGER +*> The length of WORK. LWORK >= (N+NB+1)*(NB+3). +*> +*> If LDWORK = -1, then a workspace query is assumed; +*> the routine only calculates the optimal size of the optimal +*> size of the WORK array, returns this value as the first +*> entry of the WORK array, and no error message related to +*> LWORK is issued by XERBLA. +*> \endverbatim +*> +*> \param[out] INFO +*> \verbatim +*> INFO is INTEGER +*> = 0: successful exit +*> < 0: if INFO = -i, the i-th argument had an illegal value +*> > 0: if INFO = i, D(i,i) = 0; the matrix is singular and its +*> inverse could not be computed. +*> \endverbatim +* +* Authors: +* ======== +* +*> \author Univ. of Tennessee +*> \author Univ. of California Berkeley +*> \author Univ. of Colorado Denver +*> \author NAG Ltd. +* +*> \date November 2016 +* +*> \ingroup singleSYcomputational +* +*> \par Contributors: +* ================== +*> \verbatim +*> +*> November 2016, Igor Kozachenko, +*> Computer Science Division, +*> University of California, Berkeley +*> +*> \endverbatim +* +* ===================================================================== + SUBROUTINE SSYTRI_3( UPLO, N, A, LDA, E, IPIV, WORK, LWORK, + $ INFO ) +* +* -- LAPACK computational routine (version 3.7.0) -- +* -- LAPACK is a software package provided by Univ. of Tennessee, -- +* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- +* November 2016 +* +* .. Scalar Arguments .. + CHARACTER UPLO + INTEGER INFO, LDA, LWORK, N +* .. +* .. Array Arguments .. + INTEGER IPIV( * ) + REAL A( LDA, * ), E( * ), WORK( * ) +* .. +* +* ===================================================================== +* +* .. Local Scalars .. + LOGICAL UPPER, LQUERY + INTEGER LWKOPT, NB +* .. +* .. External Functions .. + LOGICAL LSAME + INTEGER ILAENV + EXTERNAL LSAME, ILAENV +* .. +* .. External Subroutines .. + EXTERNAL SSYTRI_3X +* .. +* .. Intrinsic Functions .. + INTRINSIC MAX +* .. +* .. Executable Statements .. +* +* Test the input parameters. +* + INFO = 0 + UPPER = LSAME( UPLO, 'U' ) + LQUERY = ( LWORK.EQ.-1 ) +* +* Determine the block size +* + NB = MAX( 1, ILAENV( 1, 'SSYTRI_3', UPLO, N, -1, -1, -1 ) ) + LWKOPT = ( N+NB+1 ) * ( NB+3 ) +* + IF( .NOT.UPPER .AND. .NOT.LSAME( UPLO, 'L' ) ) THEN + INFO = -1 + ELSE IF( N.LT.0 ) THEN + INFO = -2 + ELSE IF( LDA.LT.MAX( 1, N ) ) THEN + INFO = -4 + ELSE IF ( LWORK .LT. LWKOPT .AND. .NOT.LQUERY ) THEN + INFO = -8 + END IF +* + IF( INFO.NE.0 ) THEN + CALL XERBLA( 'SSYTRI_3', -INFO ) + RETURN + ELSE IF( LQUERY ) THEN + WORK( 1 ) = LWKOPT + RETURN + END IF +* +* Quick return if possible +* + IF( N.EQ.0 ) + $ RETURN +* + CALL SSYTRI_3X( UPLO, N, A, LDA, E, IPIV, WORK, NB, INFO ) +* + WORK( 1 ) = LWKOPT +* + RETURN +* +* End of SSYTRI_3 +* + END |