How do I plot a circle with a given radius and center?

Asked by MathWorks Support Team on 26 Jul 2010

Latest activity Answered by Supoj Choachaicharoenkul on 2 Oct 2019

Accepted Answer by MathWorks Support Team

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I would like to plot a circle with a given radius and center.

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Answer by MathWorks Support Team on 3 Jan 2019

Accepted Answer

Here is a MATLAB function that plots a circle with radius 'r' and locates the center at the coordinates 'x' and 'y':

function h = circle(x,y,r)
hold on
th = 0:pi/50:2*pi;
xunit = r * cos(th) + x;
yunit = r * sin(th) + y;
h = plot(xunit, yunit);
hold off

An alternative method is to use the 'rectangle' function:

function h = circle2(x,y,r)
d = r*2;
px = x-r;
py = y-r;
h = rectangle('Position',[px py d d],'Curvature',[1,1]);
daspect([1,1,1])

If you are using version R2012a or later and have Image Processing Toolbox, then you can use the 'viscircles' function to draw circles:

viscircles(centers,radii)

7 Comments

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Walter Roberson on 25 Oct 2016

bushra mughai, see http://matlab.wikia.com/wiki/FAQ#How_do_I_create_a_circle.3F

Chinthamakula Saikiran on 26 Jul 2017

Thanks and we want answer to plot circle when they have given us centre and a point on the circle

Michael Abboud on 1 Aug 2017

If you would like to plot a circle given two points [Center, Point on circle], rather than [Center, Radius], you can simply calculate the distance between your two points, and then use that distance as the radius.

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Answer by serwan Bamerni on 17 Feb 2016

There is now a function called viscircles():

http://www.mathworks.com/help/images/ref/viscircles.html?s_tid=srchtitle

2 Comments

Walter Roberson on 17 Oct 2016

This is part of the Image Processing Toolbox

ceethal piyus on 16 May 2019

I've applied circular hough tranform for identifing the circlular objects in an image and i got the results . But when i used the code into an app designer, insted of ploting the circles into the image where the centers are marked its ploting the circle in a different figure. How can i get both circles and center points into the same axes ( named "app.segmented" )

error

How to add the axes name to viscircles function in an app designer. I tired

viscircles(centres,radii,'color','b','parent','app.segemented'); which is giving the following error.

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Answer by amine bouabid on 23 Jul 2018

Edited by amine bouabid on 23 Jul 2018

hello

you can plot a circle simply by writing :

    syms x; syms y;
    ezplot((x-xi).^2+(y-yi).^2-r.^2)

where xi and yi are the coordinates of the center and r is the radius

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Answer by Supoj Choachaicharoenkul on 2 Oct 2019

plot(x, y, 'bo', 'MarkerSize', 50);

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