ZLANGB  -  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

       DOUBLE PRECISION FUNCTION ZLANGB( NORM,  N,  KL,  KU,  AB,
                        LDAB, WORK )

           CHARACTER    NORM

           INTEGER      KL, KU, LDAB, N

           DOUBLE       PRECISION WORK( * )

           COMPLEX*16   AB( LDAB, * )


PURPOSE

       ZLANGB 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

       ZLANGB returns the value

          ZLANGB = ( 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 ZLANGB as
               described above.

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

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


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

       AB      (input) COMPLEX*16 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) DOUBLE PRECISION array, dimension
               (LWORK),
               where LWORK >= N when NORM = 'I'; otherwise,  WORK
               is not referenced.


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