clantp(3F)

NAME
     CLANTP - return 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

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

         CHARACTER DIAG, NORM, UPLO

         INTEGER   N

         REAL      WORK( * )

         COMPLEX   AP( * )

PURPOSE
     CLANTP  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
     CLANTP returns the value

        CLANTP = ( 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 CLANTP 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 triangular.  = 'N':
             Non-unit triangular
             = 'U':  Unit triangular
     N       (input) INTEGER
             The order of the matrix A.  N >= 0.  When N = 0, CLANTP is set to
             zero.

     AP      (input) COMPLEX 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.