Is this code good enough for illustrate gradient descent

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This is my code for 15 iterative steps
clf
X = -3:0.1:3;
[X,Y] = meshgrid(X);
Z = 4*X.^2-4*X.*Y+2*Y.^2;
surf(X,Y,Z,'FaceColor','c','FaceAlpha',0.3,'EdgeColor','none');
hold on
x(1) = 2; % initial value of x
y(1) = 3; % initial value of y
z(1) = 4*(x(1)).^2-4*(x(1)).*(y(1))+2*(y(1)).^2;
stepsize = 0.1;
for i = 1:15
zx = 8*x(i)-4*y(i);
zy =-4*x(i)+4*y(i);
x(i+1) = x(i) - stepsize*zx; %gradient descent
y(i+1) = y(i) - stepsize*zy;
z(i+1) = 4*(x(i+1)).^2-4*(x(i+1)).*(y(i+1))+2*(y(i+1)).^2;
end
plot3(x,y,z,'o','Markersize',3,'Color','red')
hold off
axis([min(x),max(x), min(y),max(y), min(z), max(z)]);
rotate3d on;
xlabel x; ylabel y; zlabel z;
I get this figure
I dont know if this illustration good enough
  2 Comments
Adam Danz
Adam Danz on 6 Aug 2022
Edited: Adam Danz on 7 Aug 2022
In my opinion, instead of setting EdgeColor to None, it would look better if you set EdgeAlpha to something like 0.4. It will help to show the 2D structure of the surface. You may want to set the viewing angle (view) if you need a specific vantage point.

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