clear all;
close all;
clc;

dx = 0.01;

x = -10:dx:10;

y = 2*x.*x.*x + x + 3;

%Derivace
for I=2:size(y,2)
    dy(I) = (y(I) - y(I-1)) / dx;
end

subplot(1,3,1);
plot(x,y, 'b')

subplot(1,3,2);
plot(x, dy, 'g')

dy2 = 6*x.*x+1;
subplot(1,3,3);
scatter(x, dy2, 'r')