could you help me with this explanation?

OverallEffectinevess = (MassFlowFunction*ConvectionCoolingEfficiency)/(1 + MassFlowFunction*ConvectionCoolingEfficiency);
MetalTemperature = (ExternalGasTemperature) - OverallEffectinevess*(ExternalGasTemperature-CoolantInletTemperature);

Error using *

Incorrect dimensions for matrix multiplication. Check that the number of columns in the first matrix matches the number of rows in the second matrix. To perform elementwise multiplication, use '.*'.

Answer 1

[James Tursa]

It's possible you just need to switch to element-wise operators. E.g.,

OverallEffectinevess = (MassFlowFunction.*ConvectionCoolingEfficiency)./(1 + MassFlowFunction.*ConvectionCoolingEfficiency);
MetalTemperature = (ExternalGasTemperature) - OverallEffectinevess.*(ExternalGasTemperature-CoolantInletTemperature);

What are the sizes of your variables?

[isilay aydin]

each variable of first line is 10x1

each variable of second line is 1x1

[Walter Roberson]

In MATLAB, C = A*B is algebraic matrix multiplication, also known as Inner Product.

C(I,J) = sum(A(I,:) .* B(:,J).')

In order for this to work, size(A,2) must be the same as size (B,1)

When you have A is a (10 x 1), B is a (10 x 1), then size(A,2) is 1, and size(B,1) is 10, and 1 is not equal to 10 so that is an error. You could have A*B' giving a 10 x 10 result, or you could have A'*B giving a 1 x 1 result, but not A*B .

If you want to multiple each element by its corresponding element, C(I,J) = A(I,J) * B(I,J) then you need the .* operator, MassFlowFunction.*ConvectionCoolingEfficiency not MassFlowFunction*ConvectionCoolingEfficiency

[isilay aydin]

thank you so much