Interpolacja

zadanie5.m

clear;
global n = 50;
x = sort(rand(1,n).*10);
y = rand(1,n).*20-10;

function f = nwtn(x,known_x,a)
	global n;
	f = 0;
	for i=1:n
		elem = a(i);
		for j=1:i-1
			elem = elem * (x-known_x(j));
		endfor
		f = f +  elem;
	endfor
endfunction

for i=1:n
	a = y;
	for j=2:n
		for k=n:-1:j
			a(k)=(a(k)-a(k-1))/(x(k)-x(k-j+1));
		endfor
	endfor
endfor

xx = -1:0.01:11;
i = 0;

for x_=xx
	yy(++i) = nwtn(x_,x,a);
endfor
plot(x,y,"x","markersize", 20,xx,yy);
axis([0, 11, -11, 11]);