Points on a circle

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Stefan Juhanson
Stefan Juhanson 2021-5-24
回答： Adam Danz 2021-5-24
Hello everyone!
how can i get a random point on the min and max circles on these:
format short
A = load('C:\Users\Stefan\Desktop\MatiValjasMatLAb/vruut.txt')
nurgad=A(:,1)
kaugused=A(:,2)
%polarplot(nurgad,kaugused,'o')
%Joonise järgi võiks lähendada ringjoonega
%Arvandmete järgi võiks ka eeldada, et saab lähendada ringjoonega
%sest raadiused ei kõigu palju.
%joonised
x = kaugused.*cos(nurgad); y = kaugused.*sin(nurgad);
plot(x,y,'.')
axis equal
hold on
c = [x y ones(length(x),1)]\-(x.^2+y.^2); %vähim ruutude meetod
xhat = -c(1)/2;
yhat = -c(2)/2;
raadius = sqrt(xhat^2+yhat^2-c(3));
plot(raadius*cos(nurgad)+xhat,raadius*sin(nurgad)+yhat,...
'g','linewidth',1) %parim ring(best fit circle)
hold on
ax = gca;
ax.XAxisLocation = 'origin';
ax.YAxisLocation = 'origin';
raadius
kesk=[xhat, yhat]
plot(xhat,yhat,'O')
hold on
B=max(kaugused);
C=min(kaugused);
theta=0:0.01:2*pi;
xmax=B*cos(theta)+xhat;
ymax=B*sin(theta)+yhat;
plot(xmax,ymax)
hold on
hold on
xmin=C*cos(theta)+xhat;
ymin=C*sin(theta)+yhat;
plot(xmin,ymin)
hold on
hold off
The plot looks like this :

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采纳的回答

Adam Danz
Adam Danz 2021-5-24
Ran in:
These lines define your circle for each point theta
xmax=B*cos(theta)+xhat;
ymax=B*sin(theta)+yhat;
All you need to do is define theta as random values between 0 and 2pi to plot random points on the circle.
B = 5;
xhat = 3;
yhat = -2;
theta = linspace(-pi,pi,500);
xmax=B*cos(theta)+xhat;
ymax=B*sin(theta)+yhat;
plot(xmax,ymax)
axis equal
n = 20; % number of random points
rng('default')
thetaRand = rand(1,n) * 2*pi;
xp=B*cos(thetaRand)+xhat;
yp=B*sin(thetaRand)+yhat;
hold on
plot(xp,yp,'o')

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