Using imported data in an equation

I have an equation with several known constants and three variables; efficiency, Cp and T1. I am trying to calculate efficiency. I have attached an image of the equation.

However, Cp changes depending on T1. I have imported an excel spreasheet that gives the values of Cp at a variety of temperatures.

How do I use MATLAB to calculate efficiency at the specified combinations of T1 and Cp so that I can plot a graph of T1 against efficiency?

Answer 1

[Cris LaPierre]

I would create a vector of T1 values, and a vector of the corresponding cp values. I would then compute efficiency using the vectors of T1 and cp. If the equation is set up properly using array (elementwise) operations, efficiency should be a vector the same size as T1.

From there, you can use the plot command.

See Ch 6 of MATLAB Onramp for more on array calculations.

[Tom Morris]

When I set the two variables as arrays, both (29x1 double), my resulting efficiency value is a (29x29) .

This is the equation

Eff1=1-((((cp.*T.*(Vr.^(R./cp))+(((((2.*l.*S1)./n)-((S1+Ve)./(pi.*rb.^2))).^2)/((cp.*T)+((S1.*Ve)./(sqrt(2).*n.*pi.*rb.^2)).^2))))))

All the variables apart from T, cp and Eff1 are constants.

Any idea where I'm going wrong.

[Cris LaPierre]

Sounds like a result of implicit expansion. Somewhere you are multiplying or adding a 1x29 with a 29x1, resulting in a 29x29.