Need a script to plot a circle with given radius and center

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Manu Manu
Manu Manu 2014-3-16
评论： Image Analyst 2021-8-31
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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采纳的回答

Image Analyst
Image Analyst 2014-3-16
编辑：Image Analyst 2014-3-16
See the FAQ for code examples: http://matlab.wikia.com/wiki/FAQ#How_do_I_create_a_circle.3F
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 个评论
显示 1更早的评论
Image Analyst
Image Analyst 2021-8-31
@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.

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更多回答（2 个）

Image Analyst
Image Analyst 2020-6-11
Here's another way
viscircles([5,7], 3);
  2 个评论
Tamara del Águila
Tamara del Águila 2021-5-26
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
Image Analyst 2021-5-26
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.

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Alamgir Khan
Alamgir Khan 2020-6-11
编辑：Alamgir Khan 2020-6-11
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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