clear all
close all
clc

alfa=20*pi/180;
m=6;
NP=21;
N1=10;
N2=N1+NP-1;
for i=1:NP
    N(i)=(N2-N1)/(NP-1)*(i-1)+N1;
    dp(i)=m*N(i);
    df(i)=dp(i)-2*m;
    db(i)=dp(i)*cos(alfa);
end
figure(1)
plot(N,df,N,db)
legend('df','db',4)