Unable to perform assignment because the size of the left side is 1-by-1 and the size of the right side is 10-by-10. not sure why i am getting this error

data_rho = [7840,0.44];

data_Cp = [490,0.0733333];

data_k = [13.1947,0.0126919];

%% Geometry

L = 0.03;

%% Boundary conditions

T0 = 1000;

Tinfinity = 20 + 273;

htc_top = 50;

htc_sides = 100;

htc_btm = 20;

Emissivity = 0.0;

time = 0;

%% thermocouple positions

tpx = [0.015 0.027 0.027];

tpy = [0.015 0.015 0.027];

%% Simulation control

n = 10;

CFL = 0.5;

itPlot = 10;

%% Discretize space

dx = L/(n-1);

x = 0:dx:L;

y = L:-dx:0; % T(1,1) is the top left

%% Initialize variables

T = ones(n,n)*T0;

T_new = zeros(n,n);

dtMat = zeros(n,n);

it = 0;

%% Physical constants

stefan = 5.670367e-8;

%% Record predictions

Temp_thermocouples = interp2(x,y,T,tpx,tpy);

SaveNumber = 1;

TimeVector(SaveNumber) = time;

TempSavedMatrix(SaveNumber,:) = Temp_thermocouples;

%% Model calculation

while max(max(T)) > 300 + 273.15

%% Thermophysical properties

rho = data_rho(1) + data_rho(2)*T;

k0 = data_k(1) + data_k(2)*T;

Cp = data_Cp(1) + data_Cp(2)*T;

%% Calculate temperature dependent parameters

alpha = k0./rho./Cp;

Br = stefan*Emissivity*dx./k0;

Biot_top = htc_top*dx./k0;

Biot_btm = htc_btm*dx./k0;

Biot_sides = htc_sides*dx./k0;

%% time step

for i = 2: n-1

for j = 2: n-1

dtMat(i,j) = CFL*dx*dx/4./alpha(i,j);

end

end

% top left

dtMat(1,1) = CFL*dx*dx/2./alpha(1,1)*(Biot_sides(1,1)+Biot_top(1,1)+2*Br(1,1)*T(1,1)^3);

% top edge

for j = 2: n-1

dtMat(1,j) = CFL*dx*dx/2./alpha(1,j)*(2+Biot_top+Br(1,j)*T(1,j)^3);

end

line with the error code is

for j = 2: n-1

dtMat(1,j) = CFL*dx*dx/2./alpha(1,j)*(2+Biot_top+Br(1,j)*T(1,j)^3);

end

Answer 1

[Daniel Pollard]

Biot_top is size 10x10. dtMat(1,j) is size 1x1. This means the LHS of your line is 1x1, and the RHS is 10x10, so you can't make the assignment.

I suspect you intended to write Biot_top(1,j)?