Why I can't get a line plot from this code? Moreover how can I get different color for different "q" values here?

clear all;
p=100;
for q=0:0.2:1
     for r=0:pi/6:4*pi
        s=(((1-q^2)^2)/(1+q^4-2*(q^2)*(cos(r))))*p;
        plot(r,s,'b-o','-','LineWidth',2)
        hold all;
     end
end

Answer 1

[KSSV]

q = 0:0.2:1 ;
r=0:pi/6:4*pi ;
s = zeros(length(q),length(r)) ;

for i = 1:length(q)
    s(i,:)=(((1-q(i)^2)^2)./(1+q(i)^4-2*(q(i)^2)*(cos(r))))*p;
end
plot(r,s)

[Hossen_BD]

Thanks a lot. But how can I get different colors for different lines (different "q" values)?

[KSSV]

Remove plot inside the loop...and plot outside

plot(r,s)