Plot 3D with mesh points known

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Thanasis Hou 2017-4-25

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回答： KSSV 2017-4-26

Hello,

I am encountered a problem with plotting. I solved a linear system(9x9) of equations (x = inv(A)*b). I have a 5x5 grid over 0<x<4 and 0<y<4 wiht boundary conditions. I want to depict the results in 3D. The solution gives (interior points)

x = [u2,2; u3,2; u4,2; u2,3; u3,3; u4,3; u2,4; u3,4; u4,4]

In addition, for x = 0 I have the BC points, u1,4 = u1,3 = u1,2 = 80

for x = 4, u5,4 = u5,3 = u5,2 = 0

for y = 0, u2,1 = u3,1 = u4,1 = 20

for y = 4, u2,5 = u3,5 = u4,5 = 180.

How can I make a 3D plot (surface) with these?

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KSSV 2017-4-26

Your given data is quite confusing. Note that surf plots 3D surface. Read about surf

Thanasis Hou 2017-4-26

编辑：Thanasis Hou 2017-4-26

I attached an image with the grid. I have the values of the elements of matrix x. The points of the grid have different position in the matrix.

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Answer 1

KSSV 2017-4-26

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https://ww2.mathworks.cn/matlabcentral/answers/337244-plot-3d-with-mesh-points-known#answer_264543

在 MATLAB Online 中打开

x = 0:4 ;
y = 0:4 ;
[X,Y] = meshgrid(x,y) ;
U = rand(size(X)) ;  % you have to find the interior points, I have taken random 
U(:,1) = 80 ;
U(1,:) = 180 ;
U(:,end) = 0 ;
U(end,:) = 20 ;
surf(X,Y,U)