function [c,a] = char_values(n)
%
%  function c = char_values(n)
%
% Produces the approximations to the characteristic values of 
%        2
%     d u(x)    2
%    ------- + k  u(x) = 0,  u(0) = 0 and u(1) = 0.
%         2
%      d x
%
% via finite difference method for the partition in n subintervals
%
h = 1/n;
a = diag(2*ones(1,n-1))-diag(ones(1,n-2),-1)-diag(ones(1,n-2),+1);
e = eig(a);
c2 = e/h^2;
c = sqrt(c2);