function gamma = hager(B,kl);
%
%	Hager's condition estimator to estimate the 1-norm of
%	a matrix B.
%
	[m,n] = size(B);
	x = ones(n,1)/n;
	for k = 1:kl
		y  = B * x;
		xi = sign1(y);
		z  = B' * xi;
		if (max(abs(z)) < (z' * x))
			gamma = norm(y,1);
			return
		else
			[zj,j] = max(abs(z));
			x = zeros(n,1); x(j) = 1;
		end
	end
	gamma = norm(B * x, 1);
	return

	function y = sign1(x)
%
%	defines a sign function
%
	y = x;
	n = length(x);
	for k = 1:n
		if (x(k) < 0)
			y(k) = - 1;
		else
			y(k) = 1;
		end
	end
	return