CLANGT(3)      LAPACK routine of NEC Numeric Library Collection      CLANGT(3)



NAME
       CLANGT

SYNOPSIS
       REAL FUNCTION CLANGT (NORM, N, DL, D, DU)



PURPOSE
            CLANGT  returns the value of the one norm,  or the Frobenius norm, or
            the  infinity norm,  or the  element of  largest absolute value  of a
            complex tridiagonal matrix A.


       Returns:
           CLANGT

               CLANGT = ( 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.




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

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

           DL        (input)
                     DL is COMPLEX array, dimension (N-1)
                     The (n-1) sub-diagonal elements of A.

           D         (input)
                     D is COMPLEX array, dimension (N)
                     The diagonal elements of A.

           DU        (input)
                     DU is COMPLEX array, dimension (N-1)
                     The (n-1) super-diagonal elements of A.



LAPACK routine                  31 October 2017                      CLANGT(3)