Finding number of points inside a circle and assign them into a matrix

Hi guys,

I have a grid of dots (x,y) which lies on a plane, I am creating circles in the same plane which I know both radius and center coordinates of circle.

What I am trying to do is create a new matrix of (x,y) coordinates of dots which are inside the circle.

Thanks in advance

Answer 1

[bym]

one way to do it:

clc;clear
xy = rand(100,2);
plot(xy(:,1),xy(:,2),'b.')
hold on
t = linspace(0,2*pi);
plot(.5+.25*cos(t),.5+.25*sin(t),'r-')
axis square
r = hypot(xy(:,1)-.5,xy(:,2)-.5);
plot(xy(r<=.25,1),xy(r<=.25,2),'go')

[m]

could you explain