How to Draw a Circle of Given Radius R in MATLAB?

A closed plane figure, which is formed by the set of all those points which are equidistant from a fixed point in the same plane, is called a Circle. Now we will draw a circle of a given radius R. To draw a circle below are the points or procedures to remember.

Steps:

• declare a variable that stores radius value. We can also take input from the user using the ‘input()’ function.
• use linspace() which returns a row vector of n evenly spaced points between two points and we will store these values in the vector.
• x = r * cos(theta) , which generates x-coordinates.
• y = r * sin(theta) , which generates y-coordinates.
• plot (x,y) , plot all the points (x,y).
• you can see by joining these points our circle will be drawn.

Example 1:

Matlab

% MATLAB code for draw circle

r=2;
% Create a vectortheta.
theta=linspace(0,2*pi,200);

% Generate x-coordinates.
x=r*cos(theta);

% Generate y-coordinate.
y=r*sin(theta);

% plot the circle.
plot(x,y);

 % Set equal scale on axes.
axis('equal');
title('Circle of r radius')

Output:

Explanation:

In the above, we are drawing the circle of radius 2, and after that, we are creating a vector theta and we are dividing 200 parts between 0 and 2*pi we store these parts into vectors after that generate x-coordinates and y-coordinates and simply plot the points through joining these points a circle will be drawn.

Draw Circle by Taking User Input:

For taking input from the user we use the input() command. In the Below example, we will take input from the user and then we will draw a circle.

Example 2:

Matlab

% MATLAB code for draw circle
 % taking input from user
r = input('Enter the radius of the circle: ')

% Create a vectortheta.
theta = linspace(0,2*pi,100);

% Generate x-coordinates.
x = r * cos(theta);

% Generate y-coordinate.
y = r * sin(theta);

% plot the circle.
plot(x,y);

% Set equal scale on axes.
axis('equal');

% put a title
title('Circle of the given radius r')

Output:

Enter the radius of the circle: 4.3

Above we are drawing a circle of a given radius. We are creating a vector and divide 100 parts between 0 and 2*pi and we store these parts in the vector theta, after that generate x-coordinates and y-coordinates and simply plot the points. By joining these points a circle will be drawn.