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## dlantp()

double precision function dlantp | ( | character | norm,
|  | character | uplo,
|  | character | diag,
|  | integer | n,
|  | double precision, dimension( * ) | ap,
|  | double precision, dimension( * ) | work )

DLANTP returns the value of the 1-norm, or the Frobenius norm, or the infinity norm, or the element of largest absolute value of a triangular matrix supplied in packed form.

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

Purpose:

      !>
      !> DLANTP  returns the value of the one norm,  or the Frobenius norm, or
      !> the  infinity norm,  or the  element of  largest absolute value  of a
      !> triangular matrix A, supplied in packed form.
      !>

Returns
  DLANTP

      !>
      !>    DLANTP = ( max(abs(A(i,j))), NORM = 'M' or 'm'
      !>             (
      !>             ( norm1(A),         NORM = '1', 'O' or 'o'
      !>             (
      !>             ( normI(A),         NORM = 'I' or 'i'
      !>             (
      !>             ( normF(A),         NORM = 'F', 'f', 'E' or 'e'
      !>
      !> where  norm1  denotes the  one norm of a matrix (maximum column sum),
      !> normI  denotes the  infinity norm  of a matrix  (maximum row sum) and
      !> normF  denotes the  Frobenius norm of a matrix (square root of sum of
      !> squares).  Note that  max(abs(A(i,j)))  is not a consistent matrix norm.
      !>

Parameters

  [in]

  NORM

      !>          NORM is CHARACTER*1
      !>          Specifies the value to be returned in DLANTP as described
      !>          above.
      !>

  [in]

  UPLO

      !>          UPLO is CHARACTER*1
      !>          Specifies whether the matrix A is upper or lower triangular.
      !>          = 'U':  Upper triangular
      !>          = 'L':  Lower triangular
      !>

  [in]

  DIAG

      !>          DIAG is CHARACTER*1
      !>          Specifies whether or not the matrix A is unit triangular.
      !>          = 'N':  Non-unit triangular
      !>          = 'U':  Unit triangular
      !>

  [in]

  N

      !>          N is INTEGER
      !>          The order of the matrix A.  N >= 0.  When N = 0, DLANTP is
      !>          set to zero.
      !>

  [in]

  AP

      !>          AP is DOUBLE PRECISION 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.
      !>          Note that when DIAG = 'U', the elements of the array AP
      !>          corresponding to the diagonal elements of the matrix A are
      !>          not referenced, but are assumed to be one.
      !>

  [out]

  WORK

      !>          WORK is DOUBLE PRECISION array, dimension (MAX(1,LWORK)),
      !>          where LWORK >= N when NORM = 'I'; otherwise, WORK is not
      !>          referenced.
      !>

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