Plotting Anonymous Function of two variables

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Michael Haag 2023-9-19

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2023237-plotting-anonymous-function-of-two-variables

评论： Michael Haag 2023-9-20

采纳的回答： Matt J

在 MATLAB Online 中打开

Hello,

I have defined the following Anonymous Function of two variables:

f1 = @(x) erf(x(1))+cos(x(2));

When writing the command for plotting via fsurf

fsurf(f1,[-5 0 -5 5])
Error using surf
Z must be a matrix, not a scalar or vector.

I get the following warning and my figure remains empty:

Warning: Function behaves unexpectedly on array inputs. To improve performance, properly vectorize

your function to return an output with the same size and shape as the input arguments.

So, what am I doing wrong?

I know that I can plot the function with

f1 = @(x,y) erf(x)+cos(y);
fsurf(f1,[-5 0 -5 5])

but I want to plot it like at the beginning.

How can I plot a Anonymous Function that is defined as mentioned at the beginning?

Regards,

Michael

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Dyuman Joshi 2023-9-20

"the objective function has to be defined as mentioned"

I am bit skeptical about "has to".

Can you give more details about what you are trying to? Can you share the objective function?

Michael Haag 2023-9-20

在 MATLAB Online 中打开

s = @(x1,x2) erf(x1)+cos(x2); %use this for surface plotting
objective = @(x) s(x(1), x(2)); %use this for fmincon

This is exactly what I need! Thanks a lot.

@Dyuman Joshi: I just want to minimize a simple function. My intention was to figure out how to define the function thta I am able to minimize it with fmincon and to plot it afterwards.

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采纳的回答

Matt J 2023-9-19

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2023237-plotting-anonymous-function-of-two-variables#answer_1313552

在 MATLAB Online 中打开

f1 = @(x) erf(x(1))+cos(x(2));

fsurf(@(x1,x2) f1([x1,x2]) , [-5 0 -5 5])

Warning: Function behaves unexpectedly on array inputs. To improve performance, properly vectorize your function to return an output with the same size and shape as the input arguments.