CLANGB  -  return the value of the one norm, or the Frobe­
       nius norm, or the infinity norm, or the element of largest
       absolute  value  of  an n by n band matrix A, with kl sub-
       diagonals and ku super-diagonals


SYNOPSIS

       REAL FUNCTION CLANGB( NORM, N, KL, KU, AB, LDAB, WORK )

           CHARACTER NORM

           INTEGER   KL, KU, LDAB, N

           REAL      WORK( * )

           COMPLEX   AB( LDAB, * )


PURPOSE

       CLANGB returns the value of the one norm, or the Frobenius
       norm,  or  the  infinity  norm,  or the element of largest
       absolute value of an n by n band matrix A,  with  kl  sub-
       diagonals and ku super-diagonals.


DESCRIPTION

       CLANGB returns the value

          CLANGB = ( 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   Frobe­
       nius  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  CLANGB  as
               described above.

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

       KL      (input) INTEGER
               The number of sub-diagonals of the matrix  A.   KL
               >= 0.

               The number of super-diagonals of the matrix A.  KU
               >= 0.

       AB      (input) COMPLEX array, dimension (LDAB,N)
               The band matrix A, stored in rows  1  to  KL+KU+1.
               The  j-th column of A is stored in the j-th column
               of the  array  AB  as  follows:  AB(ku+1+i-j,j)  =
               A(i,j) for max(1,j-ku)<=i<=min(n,j+kl).

       LDAB    (input) INTEGER
               The  leading  dimension  of the array AB.  LDAB >=
               KL+KU+1.

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


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