Need a script to plot a circle with given radius and center
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Manu Manu
on 16 Mar 2014
Commented: Image Analyst
on 31 Aug 2021
I need some help guys! Need a script to plot a circle with center(5,7) and radius 3. I have these:
clear clc
r=3;
t=0:pi/24:2*pi;
x=r*cos(t);
y=r*sin(t);
plot(x,y,x,y)
grid on
But only the radius works.. help please.
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Accepted Answer
Image Analyst
on 16 Mar 2014
Edited: Image Analyst
on 16 Mar 2014
Here's one way from the FAQ that is most similar to yours:
xCenter = 5;
yCenter = 7;
theta = 0 : 0.01 : 2*pi;
radius = 3;
x = radius * cos(theta) + xCenter;
y = radius * sin(theta) + yCenter;
plot(x, y);
axis square;
xlim([0 10]);
ylim([0 12]);
grid on;
axis equal;
3 Comments
Image Analyst
on 31 Aug 2021
@picheri naveen You can choose whatever angle increment you want. If you want bigger angle increments, change 0.01 to 0.3 or whatever you want. Or if you want to specify the number of segments on the circle, you can use linspace():
startAngle = 0;
endAngle = 2 * pi;
numberOfSegments = 360; % Whatever you want.
theta = linspace(startAngle, endAngle, numberOfSegments);
If the starting and ending angle are not 0 and 2*pi, then you'll get a partial circle (arc). And of course if your ending angle is more than 2*pi than your starting angle, you'll get some overlap.
The more you choose, the smoother the circle will be. Less will make it more polygon-like. For example if you had only 6 segments, it would look like a hexagon instead of a circle.
More Answers (2)
Image Analyst
on 11 Jun 2020
Here's another way
viscircles([5,7], 3);
2 Comments
Tamara del Águila
on 26 May 2021
but which units does viscircle use? When I draw a circular roi with drawcircle, and then I plot in the obtained coordinates a circle with viscircle, the size do not match...
Image Analyst
on 26 May 2021
I believe they both use units of whatever the axes control is using. I think they should be the same. Post a small snippet of your code showing how you compute "size" and a screenshot showing the different circle sizes.
Alamgir Khan
on 11 Jun 2020
Edited: Alamgir Khan
on 11 Jun 2020
In parametric form of the circle of radius 1, at centred(0,0) x=cos(2 pi×t) and y=sin(2pi ×t) using ezplot command
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