error: Unable to perform assignment because the size of the left side is 1-by-49 and the size of the right side is 1-by-51 at line 23, where is the problem?

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Kushagra Saurabh 2022-11-16

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https://ww2.mathworks.cn/matlabcentral/answers/1852928-error-unable-to-perform-assignment-because-the-size-of-the-left-side-is-1-by-49-and-the-size-of-the

评论： Kushagra Saurabh 2022-11-16

采纳的回答： VBBV

clear all;

close all;

geometry of domain

Nx = 51;

Ny = 51;

dx = 1/(Nx-1);

dy = 1/(Ny-1);

W = 0:dx:1;

H = 0:dy:1;

boundary and initial condition

T(10,25) = 2.5;

T(13,13) = -0.5;

T(5,38) = -2.5;

TL = 1;

TR = cos(6*3/2*3.14*H);

TT = 1;

TB = 1+W;;

T(1,2:Ny-1) = TL;

T(2:Nx-1,Ny) = TT;

T(Nx,2:Ny-1) = TR;

T(2:Nx-1,1) = TB;

T(1,1) = (TL+TB)/2;

T(Nx,1) = (TR+TB)/2;

T(1,Ny) = (TL+TT)/2;

T(Nx,Ny) = (TR+TT)/2;

Computation

Epsilon = 1e-7;

Error = 5;

Iteration = 0;

while(Error>Epsilon)

Iteration = Iteration + 1;

T_old = T;

for j = 2:Ny-1

for i = 2:Nx-1

T(i,j) = (T(i+1,j)+T(i-1,j)+T(i,j+1)+T(i,j-1))/4;

end

Error = sqrt(sumsqr(T-T_old));

end

plotting the results

colormap("jet");

contourf(W,H,T');

colorbar

title('Temperature Distribution');

xlabel('width');

ylabel('height');

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采纳的回答

VBBV 2022-11-16

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1852928-error-unable-to-perform-assignment-because-the-size-of-the-left-side-is-1-by-49-and-the-size-of-the#answer_1101723

编辑：VBBV 2022-11-16

在 MATLAB Online 中打开

T(Nx,2:Ny-1) = TR(2:Ny-1);
T(2:Nx-1,1) = TB(2:Nx-1).';

Vectors TR and TB are of different sizes

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VBBV 2022-11-16

编辑：VBBV 2022-11-16

在 MATLAB Online 中打开

If you had tried you wouldn't get same error in same line

clear all;

close all;

% geometry of domain

Nx = 51;

Ny = 51;

dx = 1/(Nx-1);

dy = 1/(Ny-1);

W = 0:dx:1;

H = 0:dy:1;

% boundary and initial condition

T(10,25) = 2.5;

T(13,13) = -0.5;

T(5,38) = -2.5;

TL = 1;

TR = cos(6*3/2*3.14*H);

TT = 1;

TB = 1+W;

T(1,2:Ny-1) = TL;

T(2:Nx-1,Ny) = TT;

T(Nx,2:Ny-1) = TR(2:Ny-1);

T(2:Nx-1,1) = TB(2:Nx-1).';

T(1,:) = (TL+TB)/2;

T(:,1) = (TR+TB)/2;

T(1,Ny) = (TL+TT)/2;

T(Nx,:) = (TR+TT)/2;

% Computation

Epsilon = 1e-7;

Error = 5;

Iteration = 0;

while(Error>Epsilon)

Iteration = Iteration + 1;

T_old = T;

for j = 2:Ny-1

for i = 2:Nx-1

T(i,j) = (T(i+1,j)+T(i-1,j)+T(i,j+1)+T(i,j-1))/4;

end

Error = sqrt(sumsqr(T-T_old));

end

% plotting the results

colormap("jet");

contourf(W,H,T');

colorbar

title('Temperature Distribution');

xlabel('width');

ylabel('height');

Kushagra Saurabh 2022-11-16

Thank you so much

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