Question

matlab中 作出函数f(x,y)=y^3/9+3*x^2*y+9*x^2+y^2+x*y+9,-2

Answer 1

[x,y]=meshgrid(linspace(-2,1,30),linspace(-7,1,30));

f=y.^3/9+3*x.^2.*y+9.*x.^2+y.^2+x.*y+9;

surf(x,y,f);

MAX=imregionalmax(f);

for i=1:1:30

for j=1:1:30

if(MAX(i,j)==1)

hold on;

plot3(x(i,j),y(i,j),f(i,j),'r*');

text(x(i,j),y(i,j),f(i,j),'极大值点');

end

end

end