i am trying to put my level curves and gradient vectors on same figure but i can't

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Kuatra Patil 2019-4-20

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/457570-i-am-trying-to-put-my-level-curves-and-gradient-vectors-on-same-figure-but-i-can-t

评论： Star Strider 2019-4-20

well, it is a simple question i am new in MATLAB. i cannot put my gradient vectors and level curves on same figure, please help me.

here is my code.

f=@(x,y) 16*y.^2 + 9*x.^2;
g= gradient(f, [x, y])
figure(1)
[X, Y] = meshgrid(-1:.1:1,-1:.1:1);
z=f(X,Y);
contour(X,Y,z,[0:10])
G1 = subs(g(1), [x y], {X,Y});
G2 = subs(g(2), [x y], {X,Y});
quiver(X, Y, G1, G2)

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Answer 1

Star Strider 2019-4-20

1
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/457570-i-am-trying-to-put-my-level-curves-and-gradient-vectors-on-same-figure-but-i-can-t#answer_371499

在 MATLAB Online 中打开

Your current approach is not going to work.

Try this instead:

f=@(x,y) 16*y.^2 + 9*x.^2;
g = @(z) gradient(z)
figure(1)
[X, Y] = meshgrid(-1:.1:1,-1:.1:1);
z=f(X,Y);
contour(X,Y,z,[0:10])
hold on
[G1,G2] = gradient(z);
quiver(X, Y, G1, G2)
hold off
axis equal