Matlab for loop plotting, how to join all the points. Please help

 E = 200000;
fex = (pi^2*E)/((le/rx)^2);
fey = (pi^2*E)/((le/ry)^2);
fe = min(fex,fey);
if fy/fe <= 2.25
    fcr = (0.658^(fy/fe))*fy;
else fcr = 0.877*fe;
end
if bf/(2*tf) <= 0.56*sqrt(E/fy)
    Qs = 1;
elseif bf/(2*tf) > 0.56*sqrt(E/fy) && bf/(2*tf) < 1.03*sqrt(E/fy)
        Qs = 1.415-0.74*(bf/(2*tf))*sqrt(fy/E);
    else
        Qs = (0.69*E)/(fy*(bf/(2*tf))^2);
end
if d1/tw >= 1.49*sqrt(E/fcr)
    beu = 1.92*tw*sqrt(E/fcr)*(1-0.34/(d1/tw)*sqrt(E/fcr));
    if beu > d1
        beu = d1;
    end
else beu = d1;
end
Qa = beu/d1;
Q = Qs*Qa;
if (Q*fy)/fe <= 2.25
    fcrn = Q*(0.658^((Q*fy)/fe))*fy;
else
    fcrn = 0.877*fe;
end
pn = fcrn*Ag;
usa = 0.9*pn*10^-3;
hold on
p3 = plot(le,usa,'xk');
hold off

Im getting all the points but how can I join the points together to form a smooth line?

[KSSV]

what is le,rx,ry,fx,fy? Many parameters are not given above... If your le, usa are arrays use plot(le,us) to plot them in lines.