Question

matlab如何画z=x^2+y^2,z<=5,的曲面图？

Answer 1

x=linspace(-2.5,2.5); y=linspace(-2.5,2.5); z=x.^2+y.^2;
[X,Y]=meshgrid(x,y);[X1,Y1,Z1]=meshgrid(x,y,5);
Z=X.^2+Y.^2;
mesh(X,Y,Z);hold on
mesh(X1,Y1,Z1);

Answer 2

x=[-sqrt(5):0.01:sqrt(5)];
y=[-sqrt(5):0.01:sqrt(5)];
[xx,yy]=meshgrid(x,y);
[m,n]=size(xx);
for i=1:m
for j=1:n
z(m,n)=x(m,n)^2+y(m,n)^2;
if(z(m,n)>5) z(m,n)=nan;end
end
end

surf(xx,yy,z);
以上函数是我凭记忆写的，可能用法有点问题，你最好是查找help调试下