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?

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

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');

Answer 1

[VBBV]

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

[Kushagra Saurabh]

So, what changes do I have to make?

[VBBV]

Did you try above change ?

[VBBV]

T(1,1) = (TL+TB)/2; % this
T(Nx,1) = (TR+TB)/2;
T(1,Ny) = (TL+TT)/2;
T(Nx,Ny) = (TR+TT)/2;

You would also need changes in these lines

[Kushagra Saurabh]

I tried, but now it's giving an error: Unable to perform assignment because the size of the left side is 1-by-50 and the size of the right side is 1-by-49 at line 23, where is the problem?

[VBBV]

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
    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]

Thank you so much