find a max value in function

Question

In Yeob Kim 2019-5-22

编辑： madhan ravi 2019-5-22

[x,y] = meshgrid(-2 : 0.5 : 2 , -5 : 0.5 : 5);
z = ( 5*x.^2 )+( y.^3 )+10*x;
mesh(x,y,z);
xlabel('x-axis');
ylabel('y-axis');
zlabel('z-axis');

i'm troble in this problem

i ask something this problem, present i make a 3dimension function graph

and i want find a max value , min value in z and add mark to max value , min value

please help me

i'm not good at englinsh. sorry

Answer 1

madhan ravi 2019-5-22

Add the below after mesh() call:

mx = z==max(z(:));
mn = z==min(z(:));
hold on
plot3(x(mx),y(mx),z(mx),'ok')
plot3(x(mn),y(mn),z(mn),'or')

madhan ravi 2019-5-22

If you have repeated max or min use find()

mx = find(z==max(z(:)));
mn = find(z==min(z(:)));

In Yeob Kim 2019-5-22

编辑：madhan ravi 2019-5-22

‘ok’ ravi thanks i appreciate with your answer thanks see you again bye hahaha