close all; clc; clear; 

% Problem EPage 46
% 
n = 20;
E = c_2_p_10_mk_E(n);
approx_inv = inv(E);
exact_inv = diag( 2*ones(1,n) ) - diag( ones(1,n-1), +1 ) - diag( ones(1,n-1), -1 );
norm( approx_inv - exact_inv ) 

n = 50;
E = c_2_p_10_mk_E(n);
approx_inv = inv(E);
exact_inv = diag( 2*ones(1,n) ) - diag( ones(1,n-1), +1 ) - diag( ones(1,n-1), -1 );
norm( approx_inv - exact_inv )