function lab4
X = [-2 -1 0 1 2];
Y = [0 0 1 1 3];

mean(X)
mean(Y)

var(X)
var(Y)

cov_matrix = cov(X,Y)

r = corrcoef(X,Y)
r(1,2);
plot(X,Y,'b*')
hold on;
p = polyfit(X,Y,1)
p(1),p(2)
a = min(X):0.01:max(X);
b = p(1)*a + p(2);
plot(a,b,'r-');

v =polyval(p, [2.5, 3])
disp(v)