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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( * )



     #include <sunperf.h>

     double slantp(char norm, char uplo, char diag, int n,  float
               *ap) ;

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 ele-
               ments  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.

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