Question

如何用matlab在一个以（2，2）为圆心，r=2的圆内产生1000个随机数，作图，

并标记出圆内距离（0,0）点距离最近的点，和距离（2，2）最远的点

Answer 1

theta = linspace(0,2*pi,1000);

r = 2;

rrr = r*ones(1,length(theta));

[x0,y0] = pol2cart(theta,rrr);

x0 = x0+2;

y0 = y0+2;

rho = r*rand(1,length(theta));

[x,y] = pol2cart(theta,rho);

x = x+2;

y = y+2;

dd = real(sqrt(x.^2+y.^2));

dmax = max(dd); dmaxid = find(dd==dmax);

dmin = min(dd); dminid = find(dd==dmin);

hold on;

plot(x0,y0,'b:');

plot(x,y,'g.');

plot(x(dmaxid),y(dmaxid),'bo');

plot(x(dminid),y(dminid),'ro');

plot(r,r,'ko');

legend('圆范围','圆内随机点',...

    ['最远点: ' num2str(dmax)],...

    ['最近点: ' num2str(dmin)],...

    '圆心',2);

axis equal;

axis([-1 5 -1 5]);

hold off;