why won't Matlab plot anything?

thetaP=linspace(0, 2*pi);
plot(R1*cos(thetaP), R1*sin(thetaP), '-b', ...
    R2*cos(thetaP), R2*sin(thetaP), '-r')

when R1 and R2 are defined

Answer 1

[Kojiro Saito]

Your code works fine.

R1=5;
R2=7;
thetaP=linspace(0, 2*pi);
plot(R1*cos(thetaP), R1*sin(thetaP), '-b', ...
        R2*cos(thetaP), R2*sin(thetaP), '-r')

Possibly, figure is being off. Please try adding figure before plot.

figure;
plot(R1*cos(thetaP), R1*sin(thetaP), '-b', ...
        R2*cos(thetaP), R2*sin(thetaP), '-r')