clear all; close all;
N = 200; x = linspace(-1,1,N);
dx = x(2)-x(1);
n0 = 100;
m = N-2;
% Diagnols
for j = 1:m
 A(j,j) = -2+dx^2*n0;
end
for j = 1:m-1
 A(j,j+1) = 1;
 A(j+1,j) = 1;
end
[V,D] = eig(A);