MATLAB: How to draw a circle in a log-log plot

Question

Hello guys, I need to make a graph that shows two concentric circles of very different sizes. I need to draw a concentric circles in a log-log plot. How can I do?

Answer 1

Use the FAQ to draw a circle, then exponentiate:

http://matlab.wikia.com/wiki/FAQ#How_do_I_create_a_circle.3F

xCenter = 12;
yCenter = 10;
theta = 0 : 0.01 : 2*pi;
radius = 5;
x = radius * cos(theta) + xCenter;
y = radius * sin(theta) + yCenter;
xe = exp(x);
ye = exp(y);
loglog(xe, ye, 'LineWidth', 2);
axis square;
grid on;
hold on;
% Draw second circle
radius = 3;
x = radius * cos(theta) + xCenter;
y = radius * sin(theta) + yCenter;
xe = exp(x);
ye = exp(y);
loglog(xe, ye, 'LineWidth', 2);