Plot a function of two variables

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SA 2021-3-13

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/771878-plot-a-function-of-two-variables

评论： SA 2021-3-13

采纳的回答： Cris LaPierre

I want to plot the function sin(4*pi*x)*sin(4*pi*y).

I tried the following but I am not sure if I am doing the right thing. Any help will be appreciated. Thanks

h = 2/11;

x = -1+h:h:1-h;

y = x;

[X,Y] = meshgrid(x,y);

z = @(x,y) sin(4*pi*x).* sin(4*pi*y); % Create Function

plot(x, z(X,Y))

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Cris LaPierre 2021-3-13

编辑：Cris LaPierre 2021-3-13

What are you trying to do? Describe that, and then we can tell you if you are doing the right thing.

SA 2021-3-13

The function sin(4*pi*x)*sin(4*pi*y) is the exact solution to a Poisson equation and I want to plot the exact solution given the domain -1<=x<=1 and -1<=y<=1 and a dimension of 11 in both directions.

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Answer 1

Cris LaPierre 2021-3-13

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I think you want to plot a surface rather than a line plot. Use surf with inputs X, Y and z. This will allow you to see the response over the full X-Y parameter space. Since the number of points will affect the resolution of this surface, I use linspace instead of the colon operator.

h = 2/11;

x = linspace(-1+h,1-h,50);

y = x;

[X,Y] = meshgrid(x,y);

z = @(x,y) sin(4*pi*x).* sin(4*pi*y); % Create Function

surf(X,Y,z(X,Y))