% Matlab diary from cs110a, Feb 18 2005.
%
% This is what I typed in class.  
%
% Type it into Matlab yourself to
% reproduce the output I showed.

load censusdata
who
s = (t-1950) /50;
A = [s .^ 3 , s .^ 2 , s , ones(11,1)];
size(A)
[m n] = size(A)
size(y)
p = A \ y
clc
qrsteps(A);
clc
qrsteps(A,y);
[R, z] = qrsteps(A,y)
R1 = R(1:n, :)
R2 = R(n+1:m, :)
z
z1 = z(1:n)
z2 = z(n+1 : m)
R1
p = R1 \ z1
A \ y
norm ( A * p - y)
R*p - z
norm(z2)
norm(R*p - z)
A
[Q, R] = qr(A);
Q
R
clc
size(Q)
Q' * Q
I = eye(11)
Q' * Q - I
rank(Q)
cond(Q)
clc
swinger