function []=prob_9_1_2()
%
% Written by:
% -- 
% John L. Weatherwax                2006-12-14
% 
% email: wax@alum.mit.edu
% 
% Please send comments and especially bug reports to the
% above email address.
% 
%-----
  
clc; close all; 

disp( 'the (3x3) Hilbert matrix' ); 
A = hilb(3)

% the exact inverse: 
disp( 'the exact Hilbert inverse' ); 
AInv = invhilb(3)

% rounding A to three significant digits: 
disp( 'rounding A to three significant digits' ); 
Achop = chop(A,3)

% the inverse of the rounded matrix:
disp( 'the inverse of the rounded matrix' );
inv(Achop)

disp( 'the difference between the computed inverse and the exact inverse' ); 
AInv-inv(Achop)

disp( 'the condition number of hilb(3)' ); 
condest(A)