Plotting a set of rings using a single function

1 view (last 30 days)
How to plot a set of rings (see the Figure below) using a single function, i.e., through the use of "for" loop?

Accepted Answer

VBBV
VBBV on 14 Aug 2020
Edited: VBBV on 14 Aug 2020
See also the m file for the code
clearvars close all
x = -100:0.5:200;
y = -100:0.5:200;
r = 50;
theta = 0:0.1:360;
for i = 1:length(x)
for k = 1:length(y)
if x(i) == 0 & y(k) == 0
for j = 1:length(theta)
xxc1(j) = r*cos(theta(j)) + x(i);
yyc1(j) = r*sin(theta(j)) + y(k);
end
plot(xxc1,yyc1,'b'); hold on axis([-100 200 -100 200]);
end
if x(i) == 0 & y(k) == 100
for j = 1:length(theta)
xxc2(j) = r*cos(theta(j)) + x(i); yyc2(j) = r*sin(theta(j)) + y(k);
end plot(xxc2,yyc2,'b'); hold on axis([-100 200 -100 200]);
end
if x(i) == 100 & y(k) == 0
for j = 1:length(theta)
xxc3(j) = r*cos(theta(j)) + x(i); yyc3(j) = r*sin(theta(j)) + y(k);
end
plot(xxc3,yyc3,'b'); hold on axis([-100 200 -100 200]);
end
if x(i) == 100 & y(k) == 100
for j = 1:length(theta)
xxc4(j) = r*cos(theta(j)) + x(i); yyc4(j) = r*sin(theta(j)) + y(k);
end
plot(xxc4,yyc4,'b'); hold on axis([-100 200 -100 200]);
end
end
end

More Answers (1)

Walter Roberson
Walter Roberson on 14 Aug 2020
r = 50;
viscircles([0 0; 0 2*r; 2*r 0; 2*r 2*r], [r;r;r;r], 'color','k', 'linewidth', 1)
If you need to be able to plot fewer or more circles, you need to explain the pattern.
  5 Comments
Walter Roberson
Walter Roberson on 14 Aug 2020
You have used fft() which is primarily for 1D signals. But for most of the x values, for any given x, there are either 0 or 4 associated y values. When there are multiple y values for a single x, then that is not a 1D signal.
It is possible to use fft() on a 2D signal, in which case it applies the transform along a single dimension. But if you were doing that then you would have to be very careful about what length() of the 2D signal would mean; most of the time length() would be wrong for that code.
So, what will F be, exactly: a 2D array that has circles drawn in it? If so then use insertShape https://www.mathworks.com/help/vision/ref/insertshape.html or use one of the techniques described at https://matlab.fandom.com/wiki/FAQ#How_do_I_create_a_circle.3F
Arash Ahmadivand
Arash Ahmadivand on 14 Aug 2020
Great explanation. Really appreciated Walter!

Sign in to comment.

Categories

Find more on Graphics Performance in Help Center and File Exchange

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!