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## chpcon()

subroutine chpcon | ( | character | uplo,
|  | integer | n,
|  | complex, dimension( * ) | ap,
|  | integer, dimension( * ) | ipiv,
|  | real | anorm,
|  | real | rcond,
|  | complex, dimension( * ) | work,
|  | integer | info )

CHPCON

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

Purpose:

      !>
      !> CHPCON estimates the reciprocal of the condition number of a complex
      !> Hermitian packed matrix A using the factorization A = U*D*U**H or
      !> A = L*D*L**H computed by CHPTRF.
      !>
      !> An estimate is obtained for norm(inv(A)), and the reciprocal of the
      !> condition number is computed as RCOND = 1 / (ANORM * norm(inv(A))).
      !>

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**H;
      !>          = 'L':  Lower triangular, form is A = L*D*L**H.
      !>

  [in]

  N

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

  [in]

  AP

      !>          AP is COMPLEX array, dimension (N*(N+1)/2)
      !>          The block diagonal matrix D and the multipliers used to
      !>          obtain the factor U or L as computed by CHPTRF, stored as a
      !>          packed triangular matrix.
      !>

  [in]

  IPIV

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

  [in]

  ANORM

      !>          ANORM is REAL
      !>          The 1-norm of the original matrix A.
      !>

  [out]

  RCOND

      !>          RCOND is REAL
      !>          The reciprocal of the condition number of the matrix A,
      !>          computed as RCOND = 1/(ANORM * AINVNM), where AINVNM is an
      !>          estimate of the 1-norm of inv(A) computed in this routine.
      !>

  [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
      !>

Author
  Univ. of Tennessee
  Univ. of California Berkeley
  Univ. of Colorado Denver
  NAG Ltd.