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slantp

 NAME
      SLANTP - return the value of the one norm, or the Frobenius
      norm, or the infinity norm, or the element of largest abso-
      lute value of a triangular matrix A, supplied in packed form

 SYNOPSIS
      REAL FUNCTION SLANTP( NORM, UPLO, DIAG, N, AP, WORK )

          CHARACTER DIAG, NORM, UPLO

          INTEGER   N

          REAL      AP( * ), WORK( * )

 PURPOSE
      SLANTP  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.

 DESCRIPTION
      SLANTP returns the value

         SLANTP = ( 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  matrix norm.

 ARGUMENTS
      NORM    (input) CHARACTER*1
              Specifies the value to be returned in SLANTP as
              described above.

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

      DIAG    (input) CHARACTER*1
              Specifies whether or not the matrix A is unit tri-
              angular.  = 'N':  Non-unit triangular

              = 'U':  Unit triangular

      N       (input) INTEGER
              The order of the matrix A.  N >= 0.  When N = 0,
              SLANTP is set to zero.

      AP      (input) REAL 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.

      WORK    (workspace) REAL array, dimension (LWORK),
              where LWORK >= N when NORM = 'I'; otherwise, WORK is
              not referenced.