# Unable to perform assignment because the left and right sides have a different number of elements.

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alexandra simon on 27 Feb 2020
Commented: alexandra simon on 27 Feb 2020
When the code is run, this error generates:
>> twentycells
Unable to perform assignment because the left and
right sides have a different number of elements.
Error in twentycells (line 34)
D(1) = U-su;
I attached the codes below to assist in debunking the error.
% name constant inputs:
ncells = 20;
hin = 50;
hinz = 100;
Tin = 100;
Tinz = 200;
Diam = 0.08;
L = 1;
k = 100;
P = pi*Diam;
Ac = (pi/4)*Diam.^2;
% calculate delta x (DX)
DX = L/ncells;
% mark cell centers
X(1) = 0;
for i = 2:ncells
X(i) = X(i-1) + DX;
end
% seperate math eqns to make coefficient calculations easier
Z = k/DX;
Y = (hinz*DX)/2;
W = k+Y;
V = (hinz*k)/W;
U = -V*Tinz;
sp = -hin*P*DX/Ac;
su = hin*P*T*DX/Ac;
% tridiagonal coefficients at left and right B/C's
B(1) = -Z-V+sp;
C(1) = Z;
D(1) = U-su;
A(ncells) = Z;
B(ncells) = -Z+sp;
D(ncells) = -su;
##### 2 CommentsShowHide 1 older comment
alexandra simon on 27 Feb 2020
Thank you!

Jeremy on 27 Feb 2020
Where is the definition of T? I am guessing that T is a vector, which makes su = hin*P*T*DX/Ac; a vector, and then you're trying to assign a vector to a scalar value with D(1) = U-su;

R2019b

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