zsytri2.f - Man Page



subroutine zsytri2 (UPLO, N, A, LDA, IPIV, WORK, LWORK, INFO)

Function/Subroutine Documentation

subroutine zsytri2 (character UPLO, integer N, complex*16, dimension( lda, * ) A, integer LDA, integer, dimension( * ) IPIV, complex*16, dimension( * ) WORK, integer LWORK, integer INFO)



 ZSYTRI2 computes the inverse of a COMPLEX*16 symmetric indefinite matrix
 A using the factorization A = U*D*U**T or A = L*D*L**T computed by
 ZSYTRF. ZSYTRI2 sets the LEADING DIMENSION of the workspace
 before calling ZSYTRI2X that actually computes the inverse.


          UPLO is CHARACTER*1
          Specifies whether the details of the factorization are stored
          as an upper or lower triangular matrix.
          = 'U':  Upper triangular, form is A = U*D*U**T;
          = 'L':  Lower triangular, form is A = L*D*L**T.


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


          A is COMPLEX*16 array, dimension (LDA,N)
          On entry, the NB diagonal matrix D and the multipliers
          used to obtain the factor U or L as computed by ZSYTRF.

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


          IPIV is INTEGER array, dimension (N)
          Details of the interchanges and the NB structure of D
          as determined by ZSYTRF.


          WORK is COMPLEX*16 array, dimension (N+NB+1)*(NB+3)


          LWORK is INTEGER
          The dimension of the array WORK.
          WORK is size >= (N+NB+1)*(NB+3)
          If LDWORK = -1, then a workspace query is assumed; the routine
              - the optimal size of the WORK array, returns
          this value as the first entry of the WORK array,
              - and no error message related to LDWORK is issued by XERBLA.


          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.

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.


November 2017

Definition at line 129 of file zsytri2.f.


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Referenced By

The man page zsytri2(3) is an alias of zsytri2.f(3).

Tue Nov 14 2017 Version 3.8.0 LAPACK