% Matlab diary from cs111, Oct 22 2007.
%
% This is what I typed in class.  
%
% Type it into Matlab yourself to
% reproduce the output I showed.

A = [.6 .7 ; .8 .9]
eigshow(A)
B = [2 1 ; -1 2]
eigshow(B)
b = [1 ; 7]
x = A \ b
r = b - A*x
b
bb = [ 1.01 ; 6.93]
xx = A \ bb
x = A\b
norm(x,2)
norm(x,1)
norm(x,inf)
norm(x)
x
x(2) = -199
norm(x,inf)
x(2) = -201
norm(x,inf)
max(abs(x))
norm(x,2)
sqrt ( sum (  x .^ 2))
clc
A
b
bb
norm(b)
norm(bb)
norm(b-bb)
b-bb
norm(b-bb)
norm(b-bb) / norm(b)
x = A\b
xx = A \ bb
norm(x-xx) / norm(x)
A
b = [1.3 ; 1.7]
x = A\b
bb = [1.31 ; 1.69];
norm(b-bb) / norm(b)
xx = A \ bb
norm(x-xx) / norm(x)
eigshow(A)
cond(A,2)
eigshow(B)
cond(B,2)
B
A
norm(x-xx) / norm(x)
cond(A)
norm(b-bb) / norm(b)
b
diary off