MATLAB: I want to create a circle of radius 5 and then inside this circle 3 more circles of radius 1 with different centers and then generate random points in each circle separately?please help

Question

I want to create a circle of radius 5 and then inside this circle 3 more circles with different centers of radius 1 and then generate random points in each circle separately?please help. I need to access the points of each circle separately like user co ordinate in circle 1,2 and 3. User co ordinate of bigger circle should be accessible.

Answer 1

N = 200 ;
R = 5 ;
C = [0 0] ;
th = linspace(0,2*pi,N) ;
xc = C(1)+R*cos(th) ;
yc = C(2)+R*sin(th) ;
% 
R1 = 1 ;
% get three centers inside the circel 
a = -R+R1 ; b = R-R1 ;
x = (b-a).*rand(3,1)+ a;
y = (b-a).*rand(3,1)+ a;
% get each cricle 
figure
hold on
plot(xc,yc) ;
plot(x,y,'.r')
cx = zeros(3,N) ;cy = zeros(3,N) ;
for i = 1:3
    cx(i,:) = x(i)+R1*cos(th) ;
    cy(i,:) = y(i)+R1*sin(th) ;
      plot(cx(i,:),cy(i,:),'r')
  end
  % Generate random numbers inside each circle 
  M = 100 ;
  a = -R1 ; b = R1 ;
  rr = cell(3,2) ;
  for i = 1:3
      rx = x(i)+(b-a).*rand(M,1)+ a;
      ry = y(i)+(b-a).*rand(M,1)+ a;
      idx = inpolygon(rx,ry,cx(i,:),cy(i,:)) ;
      rr{i} = [rx(idx) ry(idx)] ;
      plot(rx(idx,:),ry(idx,:),'.','color',rand(1,3))
  end