x=-8:0.3:8;y=x;[X,Y]=meshgrid(x,y);
Z=X^2+Y^2;
mesh(X,Y,Z);hold on
x=[-10 10];y=[-10 3];z=[30 35];line(x,y,z);
r0=(abs(Y-y(1)-(y(2)-y(1))/(x(2)-x(1))(X-x(1)))<=0.45)&...
(abs(Z-z(1)-(z(2)-z(1))/(x(2)-x(1))(X-x(1)))<0.45)&...
(abs(Y-y(1)-(y(2)-y(1))/(z(2)-z(1))*(Z-z(1)))<=0.45);
zz=r0.*Z;yy=r0.*Y;xx=r0.X;
plot3(xx(r0=0),yy(r0=0),zz(r0~=0),’r\’);
这个是直线与平面的,这怎么换成点向式直线与曲面的啊