% Starting diary file diary-29-Nov-2010.txt

A = [92 -144 ; -144 8] / 100

x = [1;1]
A*x

eigshow(A)
help eig
[X,D] = eig(A)
x1 = X(:,1)
x2 = X(:,2)
A * x1
A*x2

x2
norm(x2)
A*x2
y = 17*x2
A*y

n = 100
help spdiags
e = ones(n,1);
A = spdiags([-e 2*e -e], [-1 0 1], n , n);
A = full(A);
A(1:10,1:10)
close all
spy(A)

[X,D] = eig(A);
whos
X
D

x = X(:,17);
size(x)
lambda = D(17,17)
norm(A*x - lambda*x)

lambda = diag(D)
size(lambda)
plot(lambda,'.')
min(lambda)
max(lambda)

x
plot(x)
for i = 1:100,x=X(:,i);plot(x,'.');title(sprintf('%d',i));pause;end

load temperature
A = A100;
size(A)
help eigs
[X,D] = eigs(A,20,'SM');
size(A)
size(X)
size(D)
diag(D)
for i = 1:20,x=X(:,21-i);surf(reshape(x,100,100));title(sprintf('%d',i));pause;end

diary off