[求助]用surf画三维图 急！在线等

[qw11qw11]

要求三维空间上的点满足如下条件：
1.(x+sqrt(3)*d/3-s1)^2+y^2+z^2=l^2;
2.(x-sqrt(3)*d/6+s1/2)^2+(y+d/2-sqrt(3)*s1/2)^2+z^2=l^2
3.(x-sqrt(3)*d/6+s1/2)^2+(y-d/2+sqrt(3)*s1/2)^2+z^2=l^2
其中d=200;l=500; 250<=s1<=350;
程序要求：1.用球坐标来搜索 2.用mesh或surf来画三维图 3.z>0
现在我只做了当s1=250时的图，而且用plot3画的。不知道如何才能用mesh或surf来画三维图,又有250<=s1<=350条件成立。
程序如下，望高手帮助


d=200;l=500;s1=250;
a=0;i=1;m=[];n=[];n1=[];
while(a<=2*pi)
b=0;
while(b<=2*pi)
r=0;
while(r<=1000)
x=r*cos(a)*cos(b);y=r*cos(a)*sin(b);z=r*sin(a);
x1=(r+10)*cos(a)*cos(b);y1=(r+10)*cos(a)*sin(b);z1=(r+10)*sin(a);

r1=(x+sqrt(3)*d/3-s1)^2+y^2+z^2<=l^2;
t1=(x1+sqrt(3)*d/3-s1)^2+y1^2+z1^2>l^2;
r2=(x-sqrt(3)*d/6+s1/2)^2+(y+d/2-sqrt(3)*s1/2)^2+z^2<=l^2;
t2=(x1-sqrt(3)*d/6+s1/2)^2+(y1+d/2-sqrt(3)*s1/2)^2+z1^2>l^2;
r3=(x-sqrt(3)*d/6+s1/2)^2+(y-d/2+sqrt(3)*s1/2)^2+z^2<=l^2;
t3=(x1-sqrt(3)*d/6+s1/2)^2+(y1-d/2+sqrt(3)*s1/2)^2+z1^2>l^2;

r4=r1&r2&r3;
t4=t1|t2|t3;
if(r4&t4&z>0)==1
m(i)=x;n(i)=y;n1(i)=z;i=i+1;
end




r=r+10;
end

b=b+(2*pi)/360;
end

a=a+(2*pi)/360;
end



plot3(m(1:i-1),n(1:i-1),n1(1:i-1));

title('工作空间');
disp('finish')
grid on