How to make this graph ?thank you!

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[John D'Errico]

You have shown a simple 2-d difference equation, as well as what appears to be a surface plot.

However, the equation you show is not sufficient to generate the surface shown in the plot. For example, even if we assume that you are asking how to solve for the unknowns u(i,j) over that domain, what are the boundary conditions? Also, I would point out that the simple solution is u(i,j) == 0. So you may be asking to solve for the non-trivial solution to a homogeneous equation. That can be achieved by looking at the eigenvectors of the matrix describing the problem. Even easier is to use the function null to give the nontrivial solution vector.

But without sufficient information to actually know the complete problem, how can I be sure?

[felix 2018]

Thank you for your reply!And the boundary conditions you can give any values,and i want to konw how to plot this figure?my english is not well,please forgive me !

[John D'Errico]

No. You cannot choose ANY values for the boundary conditions, since that choice of boundary values will change how you solve the problem.

[felix 2018]

yes,the boundary conditions will change the result and the figure,i juat want to know how to make this code,can you help me make this code.thank you.