# How to use 2 variable in for loop?

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Upasana Baishya on 20 Aug 2022
Commented: Star Strider on 21 Aug 2022
I want to use 2 variable in for loop. If we consider a circle then in polar coordinate I've already used r variable. Now I want to consider theta too. For eg.
i = 360;
for j =1:i
n = 1.5 ;
th(j) = j*pi/180 ;
X(j) = sin(th(j)) ;
end
figure(1)
plot(th*180/pi,X) It give me a 1D line. Let us say for theta = 0. I want the whole range of theta from 0 to 360 to make it a 2D plot. How do I do that?
Upasana Baishya on 20 Aug 2022
Moved: Star Strider on 20 Aug 2022
I understood now, the question is not clear. The below image was in my mind when I asked the qiestion. Lets say for Theta= o line we have the set of value or sin function from the for loop. I wanted to expand the same value of sin(r) for theta 0 to 360 continousely. I'm showing only 4 theta position in the image. I'm aware its not going to be a simple code. I wanted have some input from others too. Upasana Baishya on 21 Aug 2022
Found the solution.
rho = linspace(0,50,100); Nrho = length(rho); lambda = 50; k = 2*pi/lambda;
S00_1 = sin(k.*rho);
phi = 0:pi/30:2*pi; Nphi = length(phi);
[Rho,Phi] = meshgrid(rho,phi);
cPhi = cos(Phi); X = Rho.*cPhi;
sPhi = sin(Phi); Y = Rho.*sPhi;
S00 = zeros(Nphi,Nrho);
for i = 1:Nphi
S00(i,:) = S00_1;
end
figure, mesh(X,Y,S00); Star Strider on 21 Aug 2022
That looks nothing like what you asked for in the earlier image!
If you want help on something in the future, ask the actual question you want an answer to.