SRC/ssytri_3x.f(3)         Library Functions Manual         SRC/ssytri_3x.f(3)

NAME
       SRC/ssytri_3x.f

SYNOPSIS
   Functions/Subroutines
       subroutine ssytri_3x (uplo, n, a, lda, e, ipiv, work, nb, info)
           SSYTRI_3X

Function/Subroutine Documentation
   subroutine ssytri_3x (character uplo, integer n, real, dimension( lda, * )
       a, integer lda, real, dimension( * ) e, integer, dimension( * ) ipiv,
       real, dimension( n+nb+1, * ) work, integer nb, integer info)
       SSYTRI_3X

       Purpose:


            SSYTRI_3X 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.

            This is the blocked version of the algorithm, calling Level 3 BLAS.

       Parameters
           UPLO

                     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.

           N

                     N is INTEGER
                     The order of the matrix A.  N >= 0.

           A

                     A is REAL array, dimension (LDA,N)
                     On entry, diagonal of the block diagonal matrix D and
                     factors U or L as computed by SYTRF_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.

           LDA

                     LDA is INTEGER
                     The leading dimension of the array A.  LDA >= max(1,N).

           E

                     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 referenced;
                     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.

           IPIV

                     IPIV is INTEGER array, dimension (N)
                     Details of the interchanges and the block structure of D
                     as determined by SSYTRF_RK or SSYTRF_BK.

           WORK

                     WORK is REAL array, dimension (N+NB+1,NB+3).

           NB

                     NB is INTEGER
                     Block size.

           INFO

                     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.

       Author
           Univ. of Tennessee

           Univ. of California Berkeley

           Univ. of Colorado Denver

           NAG Ltd.

       Contributors:


             June 2017,  Igor Kozachenko,
                             Computer Science Division,
                             University of California, Berkeley

       Definition at line 158 of file ssytri_3x.f.

Author
       Generated automatically by Doxygen for LAPACK from the source code.

LAPACK                          Version 3.12.0              SRC/ssytri_3x.f(3)