plot 3D minimum value of a function

Question

Zekun Xue 2020-2-9

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https://ww2.mathworks.cn/matlabcentral/answers/504527-plot-3d-minimum-value-of-a-function

评论： Star Strider 2020-2-10

Hello guys,

Thanks for looking over here.

I'd like to plot a minimum value, more precisely a 'platform' of a function in the 'surf' type of figure something like the graph I attached, no idea how to do it.

I appreciate if you could give me a hand.

Here I attached part of my code about what is my x and y axis:

pn1 = 0:0.1:5;
pn2 = 0:0.1:5;
[Pn1, Pn2] = meshgrid(pn1, pn2);

and what I plot in the figure:

Energy_consumption = Dm.* Pn1 + Tn.* Pn2;
surf(Pn1, Pn2, Energy_consumption);

Thanks you again.

Have a good day.

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Answer 1

dpb 2020-2-9

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https://ww2.mathworks.cn/matlabcentral/answers/504527-plot-3d-minimum-value-of-a-function#answer_414654

编辑：dpb 2020-2-9

在 MATLAB Online 中打开

Don't think it could be any easier...look at the following from one of the surf examples:

[X,Y,Z] = peaks(25);
CO(:,:,1) = zeros(25);                       % red
CO(:,:,2) = ones(25).*linspace(0.5,0.6,25);  % green
CO(:,:,3) = ones(25).*linspace(0,1,25);      % blue
hS1=surf(X,Y,Z,CO);                          % first peaks() surface; save handle for later
ZMIN=min(Z(:));                              % get the overall minimum Z
hold on                                      % ready axes to add another to it
hS2=surf(X,Y,ZMIN*ones(size(Z)));            % and add the plane at the ZMIN height

produces:

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Zekun Xue 2020-2-10

Wow, this is new to me, I definitely will try. Thank you very much!

Have a good day!

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Answer 2

Star Strider 2020-2-9

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/504527-plot-3d-minimum-value-of-a-function#answer_414657

在 MATLAB Online 中打开

Try this:

Dm = 20;                                            % Create Variable
Tn = 30;                                            % Create Variable
pn1 = 0:0.1:5;
pn2 = 0:0.1:5;
[Pn1, Pn2] = meshgrid(pn1, pn2);
Energy_consumption = Dm.* Pn1 + Tn.* Pn2;
surf(Pn1, Pn2, Energy_consumption)
hold on
E_c_min = 40;                                       % Apparently Minimum Is 40
mesh(Pn1, Pn2, ones(size(Pn1))*40)                  % Create Flat Plane At Minimum
hold off