function [Px,Py]=circle_center(Ax,Ay,Bx,By,Cx,Cy)

% [Ax,Ay], [Bx,By], [Cx,Cy] are three points on the circle
% [Px,Py] are the center of the circle

Px=-((Bx - Cx)*(Bx/2 + Cx/2) + (By - Cy)*(By/2 + Cy/2 - (Ay^2 - Bx^2 - Bx*By + Ax*Bx - By^2 + Ax*By)/(2*Ay - 2*By)))/(Cx - Bx + ((By - Cy)*(2*Ax - 2*Bx))/(2*Ay - 2*By));
Py=(Ay^2 - Bx^2 - By^2 + Ax*Bx + Ax*By - Bx*By - 2*Ax*Px + 2*Bx*Px)/(2*Ay - 2*By);


figure;
hold on;
plot(Ax,Ay,'*');
plot(Bx,By,'o');
plot(Cx,Cy,'x');
plot(Px,Py,'+');
title('Three points and computed center');
legend('A','B','C','P')


end