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## csytri()

subroutine csytri | ( | character | uplo,
|  | integer | n,
|  | complex, dimension( lda, * ) | a,
|  | integer | lda,
|  | integer, dimension( * ) | ipiv,
|  | complex, dimension( * ) | work,
|  | integer | info )

CSYTRI

Download CSYTRI + dependencies [TGZ] [ZIP] [TXT]

Purpose:

      !>
      !> CSYTRI computes the inverse of a complex symmetric indefinite matrix
      !> A using the factorization A = U*D*U**T or A = L*D*L**T computed by
      !> CSYTRF.
      !>

Parameters

  [in]

  UPLO

      !>          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.
      !>

  [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 block diagonal matrix D and the multipliers
      !>          used to obtain the factor U or L as computed by CSYTRF.
      !>
      !>          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.
      !>

  [in]

  LDA

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

  [in]

  IPIV

      !>          IPIV is INTEGER array, dimension (N)
      !>          Details of the interchanges and the block structure of D
      !>          as determined by CSYTRF.
      !>

  [out]

  WORK

      !>          WORK is COMPLEX array, dimension (2*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, 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.