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## ztpcon()

subroutine ztpcon | ( | character | norm,
|  | character | uplo,
|  | character | diag,
|  | integer | n,
|  | complex*16, dimension( * ) | ap,
|  | double precision | rcond,
|  | complex*16, dimension( * ) | work,
|  | double precision, dimension( * ) | rwork,
|  | integer | info )

ZTPCON

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

Purpose:

      !>
      !> ZTPCON estimates the reciprocal of the condition number of a packed
      !> triangular matrix A, in either the 1-norm or the infinity-norm.
      !>
      !> The norm of A is computed and an estimate is obtained for
      !> norm(inv(A)), then the reciprocal of the condition number is
      !> computed as
      !>    RCOND = 1 / ( norm(A) * norm(inv(A)) ).
      !>

Parameters

  [in]

  NORM

      !>          NORM is CHARACTER*1
      !>          Specifies whether the 1-norm condition number or the
      !>          infinity-norm condition number is required:
      !>          = '1' or 'O':  1-norm;
      !>          = 'I':         Infinity-norm.
      !>

  [in]

  UPLO

      !>          UPLO is CHARACTER*1
      !>          = 'U':  A is upper triangular;
      !>          = 'L':  A is lower triangular.
      !>

  [in]

  DIAG

      !>          DIAG is CHARACTER*1
      !>          = 'N':  A is non-unit triangular;
      !>          = 'U':  A is unit triangular.
      !>

  [in]

  N

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

  [in]

  AP

      !>          AP is COMPLEX*16 array, dimension (N*(N+1)/2)
      !>          The upper or lower triangular matrix A, packed columnwise in
      !>          a linear array.  The j-th column of A is stored in the array
      !>          AP as follows:
      !>          if UPLO = 'U', AP(i + (j-1)*j/2) = A(i,j) for 1<=i<=j;
      !>          if UPLO = 'L', AP(i + (j-1)*(2n-j)/2) = A(i,j) for j<=i<=n.
      !>          If DIAG = 'U', the diagonal elements of A are not referenced
      !>          and are assumed to be 1.
      !>

  [out]

  RCOND

      !>          RCOND is DOUBLE PRECISION
      !>          The reciprocal of the condition number of the matrix A,
      !>          computed as RCOND = 1/(norm(A) * norm(inv(A))).
      !>

  [out]

  WORK

      !>          WORK is COMPLEX*16 array, dimension (2*N)
      !>

  [out]

  RWORK

      !>          RWORK is DOUBLE PRECISION array, dimension (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.