Loading...
Searching...
No Matches

## zpttrf()

subroutine zpttrf | ( | integer | n,
|  | double precision, dimension( * ) | d,
|  | complex*16, dimension( * ) | e,
|  | integer | info )

ZPTTRF

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

Purpose:

      !>
      !> ZPTTRF computes the L*D*L**H factorization of a complex Hermitian
      !> positive definite tridiagonal matrix A.  The factorization may also
      !> be regarded as having the form A = U**H *D*U.
      !>

Parameters

  [in]

  N

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

  [in,out]

  D

      !>          D is DOUBLE PRECISION array, dimension (N)
      !>          On entry, the n diagonal elements of the tridiagonal matrix
      !>          A.  On exit, the n diagonal elements of the diagonal matrix
      !>          D from the L*D*L**H factorization of A.
      !>

  [in,out]

  E

      !>          E is COMPLEX*16 array, dimension (N-1)
      !>          On entry, the (n-1) subdiagonal elements of the tridiagonal
      !>          matrix A.  On exit, the (n-1) subdiagonal elements of the
      !>          unit bidiagonal factor L from the L*D*L**H factorization of A.
      !>          E can also be regarded as the superdiagonal of the unit
      !>          bidiagonal factor U from the U**H *D*U factorization of A.
      !>

  [out]

  INFO

      !>          INFO is INTEGER
      !>          = 0: successful exit
      !>          < 0: if INFO = -k, the k-th argument had an illegal value
      !>          > 0: if INFO = k, the leading principal minor of order k
      !>               is not positive; if k < N, the factorization could not
      !>               be completed, while if k = N, the factorization was
      !>               completed, but D(N) <= 0.
      !>

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