close all; clear; clc;
monakveti_x=[-1 1];
monakveti_y=[1 1];
rad=1;
wrewiris_centri_x=0;
wrewiris_centri_y=0;
fi=0:0.01:2*pi;
wrew_x=wrewiris_centri_x+rad*cos(fi);
wrew_y=wrewiris_centri_y+rad*sin(fi);
plot(monakveti_x,monakveti_y)
axis equal
grid on
hold on
plot(wrew_x,wrew_y)
x_1=monakveti_x(1)-wrewiris_centri_x;
x_2=monakveti_x(2)-wrewiris_centri_x;
y_1=monakveti_y(1)-wrewiris_centri_y;
y_2=monakveti_y(2)-wrewiris_centri_y;
r=rad;
[x,y,result]=circlelineintersection(x_1,x_2,y_1,y_2,r);
x=x+wrewiris_centri_x;
y=y+wrewiris_centri_y;
plot(x,y,'linewidth',4)

function [x,y,result]=circlelineintersection(x_1,x_2,y_1,y_2,r)

d_x = x_2-x_1;
d_y = y_2-y_1;
d_r = sqrt(d_x^2+d_y^2);
tt=[x_1,x_2;y_1,y_2];
D = det(tt);%x_1*y_2-x_2*y_1;
Delta=r^2*d_r^2-D^2;
if(Delta<0)
y=[];
x=[];
result=0;
return
end
if(Delta==0)
x = (D*d_y )/(d_r^2);
y = (-D*d_x)/(d_r^2);
result=1;
return
end
if(Delta>0)
x = (D*d_y - sign(d_y)*d_x*sqrt(Delta))/(d_r^2);
x = [x,(D*d_y + sign(d_y)*d_x*sqrt(Delta))/(d_r^2)];
y = (-D*d_x - abs(d_y)*sqrt(Delta))/(d_r^2);
y = [y,(-D*d_x + abs(d_y)*sqrt(Delta))/(d_r^2)];
result=2;
return
end
end