The easiest option to draw a circle, is - obviously - the
%// radius r = 2; %// center c = [3 3]; pos = [c-r 2*r 2*r]; rectangle('Position',pos,'Curvature',[1 1]) axis equal
but the curvature of the rectangle has to be set to 1!
position vector defines the rectangle, the first two values
y are the lower left corner of the rectangle. The last two values define width and height of the rectangle.
pos = [ [x y] width height ]
The lower left corner of the circle - yes, this circle has corners, imaginary ones though - is the center
c = [3 3] minus the radius
r = 2 which is
[x y] = [1 1]. Width and height are equal to the diameter of the circle, so
width = 2*r; height = width;
In case the smoothness of the above solution is not sufficient, there is no way around using the obvious way of drawing an actual circle by use of trigonometric functions.
%// number of points n = 1000; %// running variable t = linspace(0,2*pi,n); x = c(1) + r*sin(t); y = c(2) + r*cos(t); %// draw line line(x,y) %// or draw polygon if you want to fill it with color %// fill(x,y,[1,1,1]) axis equal