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

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.

Thank you in advance!

% 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;

[Andrés Castro]

Hi Alexandra:

In your code you have a mistake in su variable. The variable T is unrecognized. For this reason when you want to compute D(1), it isn't allowed.

Regards!

[alexandra simon]

Thank you!

Answer 1

[Jeremy]

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;