MATLAB: Linspace and polar coordinates

helplinspace

Hello.
I'm a little lost when it comes to using polar coordinates in matlab. How would I set up a linspace for polar coordinates? I'm also unsure of what the best method is for plotting in polar, should I use the polar command?
I've been using the code below but keep recieving an error.
x=[-2 -1 0 1 2];
y=[-2 -1 0 1 2];
%cartesian --> polar
rho=sqrt(x.^2+y.^2);
theta=atan(y./x);
%set up linspace with 10 pts
rho2=linspace(rho,rho,10) %this is where I'm confused because I don't know how to apply the conversion into linspace
theta2=linspace(theta,theta,10)
%eqns
for x=1:length(rho)
    for z=1:length(theta)
u(x,z)=sin(2*theta(z)).*cos(2*theta(z));
    end
end
%plot 
polarplot(rho2,theta2,u) %error here too?

Best Answer

I’m not certain where you’re going with your code or what you want to do with it.
Try something like this: 
x=[-2 -1 0 1 2];
y=[-2 -1 0 1 2];
%cartesian --> polar
rho=sqrt(x.^2+y.^2);
theta=atan2(y,x);
%set up linspace with 10 pts
rho2=linspace(min(rho),max(rho),10); %this is where I'm confused because I don't know how to apply the conversion into linspace
theta2=linspace(min(theta),max(theta),10);
u = @(x,z) x.*sin(2*z).*cos(2*z);
[R,T] = ndgrid(rho2, theta2);
U = u(R,T);
[X,Y,Z] = pol2cart(T,R,U);
figure
surf(X, Y, Z)
grid on
view(60,60)
.
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