MATLAB7.1 画弹簧摆的运动图,要程序!要在MATLAB7.1 上可以运行的theta0=pi

MATLAB7.1 画弹簧摆的运动图,要程序!要在MATLAB7.1 上可以运行的theta0=pi

function F = thbfun(t,u,flag,l,k,m,g)F = [u(2);u(1)*u(4)^2 + g*cos(u(3)) - k/m*(u(1) - l + m*g/k);u(4);-2*u(2)*u(4)/u(1) - g*sin(u(3))/u(1)];-------------------------------------------------------------theta0=pi/10 %\fs{初始角度,可由读者设不同的值}m = 1; k = 80; ; g = 9.8;L0 = 1; L = L0 + m*g/k; %\fs{L0为弹簧原来长度,L为弹簧静止时长度}[t,u1] = ode45('thbfun',[0 :0.005 :15],[L0 0 theta0 0],[],L,k,m,g);[y1,x1] = pol2cart(u1(:,3),u1(:,1)); y1 = -y1;%\fs{将极坐标换为直角坐标}ymax = max(abs(y1));axis([-1.2 1.2 -1.2*ymax 0.2]);%\fs{设置坐标范围}axis offtitle('弹簧摆','fontsize',14)hold on;R =0.055 ; %\fs{设置弹簧半径}yy = -L0 :0.01 :0;xx = R*sin(yy./L0*30*pi);%\fs{用正弦曲线表示弹簧}[a,r] = cart2pol(xx,yy); %\fs{用坐标变换来画初始位置的弹簧}a = a + theta0;[xx,yy] = pol2cart(a,r);%\fs{弹簧的数据}line([-1 1],[0 0],'color','r','linewidth',2)%\fs{画横杆,球与弹簧}ball = line(xx(1),yy(1),'color','r','marker','.',...'markersize',70,'erasemode','xor');ball2 = line(xx(1),yy(1),'color',[0.5 0.51 0.6],'linestyle','-',...'linewidth',1.3,'erasemode','none');spring = line(xx,yy,'color','r','linewidth',2,'erasemode','xor');pause(0.5)for i = 1 :length(t) %\fs{画出每一步的弹簧位置}yy = -u1(i,1) :0.01 :0;xx = R*sin(yy./u1(i,1)*30*pi);[a,r] = cart2pol(xx,yy);a = a + u1(i,3);[xx,yy] = pol2cart(a,r);set(ball,'XData',x1(i),'YData',y1(i));set(ball2,'XData',x1(i),'YData',y1(i));set(spring,'XData',xx,'YData',yy);drawnow;end

正好我需要