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| % ***************************************************************************
% spiral and square
% ***************************************************************************
a=1;
b=0.05;
n=1;t=0;l=0;
X = randi([-10 10],1,1);
Y = randi([-10 10],1,1);
x(n)=a*exp(b*t)*cos(t);
y(n)=a*exp(b*t)*sin(t);
long = 50; % 50 is good
while t<long
n=n+1;
while l < 0.00001 % ~ distance between two points
xx=a*exp(b*t)*cos(t);
yy=a*exp(b*t)*sin(t);
l=sqrt((xx-x(n-1))^2+(yy-y(n-1))^2);
t=t+1e-5; % reduire t pour augmenter le nombre de points (distance entre 2 pts diminuera)
end
x(n)=a*exp(b*t)*cos(t);
y(n)=a*exp(b*t)*sin(t);
d(n)=sqrt((x(n)-x(n-1))^2+(y(n)-y(n-1))^2); % distance entre points
l=0;
dy(n) = a*b*exp(b*t)*sin(t)+a*exp(b*t)*cos(t);
dx(n) = a*b*exp(b*t)*cos(t)-a*exp(b*t)*sin(t);
end
extremite = sqrt((x(n)).^2+(y(n)).^2);
square_length = 5;
% ***************************************************************************
% conserve only points into the square
% ***************************************************************************
x_square = zeros(1,2);
y_square = zeros(1,2);
t = 1;
for k = 1:length(x)
if X < x(k) && x(k) < X+square_length && Y < y(k) && y(k) < Y+square_length
x_square(t) = x(k);
y_square(t) = y(k);
t = t + 1;
end
end
% ***************************************************************************
% points selection RED = 1 BLUE = 2 BLACK = 3
% ***************************************************************************
% central point
distance = sqrt(2*(square_length^2));
point_number = 0;
for k = 1:t-1
if x_square(k) < X+2.5 && y_square(k) < Y+2.5
di = sqrt((X+2.5-x_square(k)).^2+(Y+2.5-y_square(k)).^2);
else if x_square(k) > X+2.5 && y_square(k) > Y+2.5
di = sqrt((x_square(k)-X-2.5).^2+(y_square(k)-Y-2.5).^2);
else if x_square(k) < X+2.5 && y_square(k) > Y+2.5
di = sqrt((X+2.5-x_square(k)).^2+(y_square(k)-Y-2.5).^2);
else if x_square(k) > X+2.5 && y_square(k) < Y+2.5
di = sqrt((x_square(k)-X-2.5).^2+(Y+2.5-y_square(k)).^2);
end
end
end
end
if di < distance
distance = di;
point_number = k;
end
end
% tangent points
eloignement = 100;
P1 = point_number + eloignement;
P2 = point_number - eloignement;
P3 = point_number;
% ***************************************************************************
% tangents RED = 1 BLUE = 2 BLACK = 3
% ***************************************************************************
dy = diff(y_square);
dx = diff(x_square);
true_tan1 = (dy(P1)*(x_square-x_square(P1)))/dx(P1) + y_square(P1);
true_tan2 = (dy(P2)*(x_square-x_square(P2)))/dx(P2) + y_square(P2);
true_tan3 = (dy(P3)*(x_square-x_square(P3)))/dx(P3) + y_square(P3);
coeff1 = (true_tan1(2)-true_tan1(1))/(x_square(2)-x_square(1));
xtan1 = -extremite:0.1:extremite;
ytan1 = coeff1*xtan1 + y_square(P1) - coeff1*x_square(P1);
coeff2 = (true_tan2(2)-true_tan2(1))/(x_square(2)-x_square(1));
xtan2 = -extremite:0.1:extremite;
ytan2 = coeff2*xtan2 + y_square(P2) - coeff2*x_square(P2);
coeff3 = (true_tan3(2)-true_tan3(1))/(x_square(2)-x_square(1));
xtan3 = -extremite:0.1:extremite;
ytan3 = coeff3*xtan3 + y_square(P3) - coeff3*x_square(P3);
% ***************************************************************************
% find centre
% ***************************************************************************
syms xc yc ang
t1 = [x_square(2)-x_square(1) true_tan1(2)-true_tan1(1) 0];
t2 = [x_square(2)-x_square(1) true_tan2(2)-true_tan2(1) 0];
t3 = [x_square(2)-x_square(1) true_tan3(2)-true_tan3(1) 0];
r1 = [xc-x_square(P1) yc-y_square(P1) 0];
r2 = [xc-x_square(P2) yc-y_square(P2) 0];
r3 = [xc-x_square(P3) yc-y_square(P3) 0];
scal1 = t1.*r1;
scal2 = t2.*r2;
scal3 = t3.*r3;
eq = [(scal1(1)+scal1(2))/(sqrt((t1(1))^2+(t1(2))^2)*sqrt((r1(1))^2+(r1(2))^2)) == cos(ang), (scal2(1)+scal2(2))/(sqrt((t2(1))^2+(t2(2))^2)*sqrt((r2(1))^2+(r2(2))^2)) == cos(ang), (scal3(1)+scal3(2))/(sqrt((t3(1))^2+(t3(2))^2)*sqrt((r3(1))^2+(r3(2))^2)) == cos(ang)];
centre = vpasolve(eq, [xc yc ang]);
xc = centre.xc;
yc = centre.yc;
ang = centre.ang;
r1 = [xc-x_square(P1) yc-y_square(P1) 0];
r2 = [xc-x_square(P2) yc-y_square(P2) 0];
r3 = [xc-x_square(P3) yc-y_square(P3) 0];
figure;
axis equal;
hold on
plot(x,y,'k');
plot([X X+square_length X+square_length X X],[Y Y Y+square_length Y+square_length Y],'g');
plot(0,0,'Xk');
plot(x_square,y_square,'.g')
plot(x_square(P1),y_square(P1),'Or')
plot(x_square(P2),y_square(P2),'Ob')
plot(x_square(P3),y_square(P3),'O','color',[0.5,0.7,0.7])
% plot tan
plot(xtan1,xtan1*(t1(2)/t1(1))+y_square(P1)-(t1(2)/t1(1))*x_square(P1),'r');
plot(xtan1,xtan1*(t2(2)/t2(1))+y_square(P2)-(t2(2)/t2(1))*x_square(P2),'b');
plot(xtan1,xtan1*(t3(2)/t3(1))+y_square(P3)-(t3(2)/t3(1))*x_square(P3),'color',[0.5,0.7,0.7]);
% plot radius
plot(xtan1,xtan1*(r1(2)/r1(1))+y_square(P1)-(r1(2)/r1(1))*x_square(P1),'r');
plot(xtan1,xtan1*(r2(2)/r2(1))+y_square(P2)-(r2(2)/r2(1))*x_square(P2),'b');
plot(xtan1,xtan1*(r3(2)/r3(1))+y_square(P3)-(r3(2)/r3(1))*x_square(P3),'color',[0.5,0.7,0.7]);
plot(xc,yc,'x-','color',[0.5,0.7,0.7]);
title('Error');
hold off
['xc' xc
'yc' yc
'ang' ang*180/pi
'erreur' sqrt((xc)^2+(yc)^2)] |
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