Comments on: Drawing a Circle

By: Brett

Brett — Wed, 04 Aug 2010 14:25:32 +0000

@Maarten,
Yep, _rectangle_ will do it. (You might want to re-read the first few sentences of my post above.) Sometimes, though, it is nice to be able to position circles parametrically, or with different syntax–one that gives you pointwise control over the plot, for instance.

By: Maarten

Maarten — Wed, 04 Aug 2010 11:50:07 +0000

This allows all the functionality of the rectangle command (linewidth, colors, etc.):

function circle (x,y,radius,varargin)

rectangle('position',[x-radius, y-radius, 2*radius, 2*radius],'curvature',[1 1],varargin{:});

By: sunil

sunil — Sat, 20 Feb 2010 18:20:25 +0000

a = magic(3);
sum(a)

showing type double error..

By: Brett

Brett — Fri, 27 Mar 2009 23:03:00 +0000

Jose,
You might try representing your circle(s) as polygons, then using the MATLAB function INPOLYGON. Just a thought.
Cheers,
Brett

By: Jose Manuel

Jose Manuel — Fri, 27 Mar 2009 22:46:18 +0000

Hello there

I need a matlab function to paint and store in an array all the poits INSIDE the circle.

Please, anybody could help me?

Thanks in advance

By: Brett

Brett — Tue, 15 Apr 2008 14:51:54 +0000

Ralf, of course we know (and love) the RECTANGLE command. (Follow the link in this post to “last week’s Pick of the Week.”) But options are always nice.

By: Ralf Hielscher

Ralf Hielscher — Tue, 15 Apr 2008 11:24:35 +0000

Does nobody knows the builtin MATLAB command

rectangle(‘Position’,[x,y,dx,dy],’Curvature’,[1,1])

which allows for all the builtin MATLAB options including hold? The main advantage of which is to do not use any discretization.

By: Brett

Brett — Mon, 24 Mar 2008 14:06:03 +0000

Sometimes we may focus on a submission because it is beautifully written…other times, simply because it does something useful, and does it well. Zhenhai’s “Circle” certainly fits that latter bill.

Urs, why would you necessarily think that HOLD-ing should be incorporated in the CIRCLE command? Many useful functions use PLOT commands–and in all cases it is up to the user to issue (or not, –depending on his or her desired behavior) the HOLD command.

Terry, I’m not sure there’s anything inherently easier about using complex coordinates than the very compact pol2cart that this function uses.

Sunpeng, I haven’t really played with your code, and it certainly appears that you’ve added some nice functionality. But I will note that your file requires the Image Processing Toolbox. I could argue that generic functionality like plotting a circle should be independent of that (or any) Toolbox.

By: sunpeng

sunpeng — Sat, 22 Mar 2008 06:20:13 +0000

hi Doug,

Why not have a look at “imPixelLine and imCircle” in FileExchange…

Do the same job, with more functionalities.

By: Terry

Terry — Fri, 21 Mar 2008 19:45:57 +0000

Complex coordinates are easier: Eg.
R = 10;
Center = [5,8];
plot(R/2*exp(i*linspace(0,2*pi,1000))+Center*[1 i].’,'b-’)
axis square