How do determine the maximum and minimum point form origin on a contour graph

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Chieh-Yen 2024-4-8

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https://ww2.mathworks.cn/matlabcentral/answers/2104251-how-do-determine-the-maximum-and-minimum-point-form-origin-on-a-contour-graph

评论： Chieh-Yen 2024-4-9

I have created a contour graph from the folloing code, where C_100030_alt173 is my raw data. I will return a contour plot with points containing (x, y, level). How do I find the max. and min. point from the origin (0,0). ie. how do i extract xy values for all points and do a simple (x^2+y^2)^1/2 calculation and identify the max. and min.

Thank you so much

x=(-1:1/512:1);
C_100030_alt173
c1P5_alt173=reshape(CON,[1025,1025]);
a=[0,0];
v1=[0.5,0.5];
v2=[0.11,0.11];
contour(x,x,c1P5_alt173,v1,EdgeColor="black");
hold on
contour(x,x,c1P5_alt173,v2,EdgeColor="blue");

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采纳的回答

Aquatris 2024-4-8

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2104251-how-do-determine-the-maximum-and-minimum-point-form-origin-on-a-contour-graph#answer_1438246

移动：Fangjun Jiang 2024-4-8

在 MATLAB Online 中打开

Not sure exactly what you want but contour function can give you interpolated x-y positions for a specific level. From there you can use a simple calculation to find the max distance to origin for that spefic level.

Z = peaks;

% get x-y locations of points corresponding to desiredLevel

desiredLevel = 1.949;

p = contourc(Z,desiredLevel*[1 1]);

% remove x y positions outside of [0 50] range

p(:,p(1,:)>50|p(2,:)>50) = [];

% get max distance

dist = sqrt(p(1,:).^2+p(2,:).^2);

maxDistIdx = find(dist==max(dist));

% draw contour graph

[M,c] = contourf(Z);xlim([0 50]);ylim([0 50])

hold on