1B.txt

Wp=28;
Bp=4;
Wg=5;
Bg=1;
z=0:0.05:30;
t=0:0.05:30;
pause(2);
for ti=1:length(t)
    for zi=1:length(z)
        E1(zi)=cos((Wp+Wg)*t(ti)-(Bp+Bg)*z(zi));
        E2(zi)=cos((Wp-Wg)*t(ti)-(Bp-Bg)*z(zi));
        E(zi)=2*cos(Wp*t(ti)-Bp*z(zi))*cos(Wg*t(ti)-Bg*z(zi)); %E1+E2
        En(zi)=2*cos(Wg*t(ti)-Bg*z(zi));
    end
    pause(0.05);
    subplot(3,1,1);
    plot(z,E1,"r");
    xlabel('Z-Variation');
    ylabel('Wave-1 [E1(z)]');
    hold on
    plot((Wp+Wg)/(Bp+Bg)*t(ti),1,'o',"MarkerFaceColor","red");
    hold off
    subplot(3,1,2);
    plot(z,E2,"b");
    xlabel('Z-Variation');
    ylabel('Wave-2 [E2(z)]');
    hold on
    plot((Wp-Wg)/(Bp-Bg)*t(ti),1,'o',"MarkerFaceColor","blue");
    ylim([-1,1]);
    hold off
    subplot(3,1,3);
    plot(z,E,"k");
    hold on
    plot(z,En,'--k',z,-En,'--k');
    plot(Wg/Bg*t(ti),2,'o',"MarkerFaceColor","g");
    x=Wp/Bp*t(ti);
    v=2*cos(Wg*t(ti)-Bg*x);
    plot(x,v,'o',"MarkerFaceColor","blue");
    hold off
    xlabel('Z-Variation');
    ylabel('E(z)=E1(z)+E2(z)');
    title('\color{blue}Phase Velocity \color{black}> \color{green}Group Velocity')
    drawnow limitrate;
end