Calculating values of a dependent variable at a using a range of independent variables

Question

Tom Morris 2021-3-10

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/768552-calculating-values-of-a-dependent-variable-at-a-using-a-range-of-independent-variables

评论： Tom Morris 2021-3-10

采纳的回答： Chad Greene

Hi,

I'm new to matlab so this might be very simple but....

I have this equation;

Eff=((Cv.*Temp.*(1-Vr))+(((2.*l.*S.*S)./(n.*n))*((Vi./(pi.*Rb.*Rb))-l))+(M./(R.*Temp))+((Vr^(1-k)).*(R.*Temp./M)))/((Cv.*Temp)+((R.*Temp)./M)+(((S.*Vi)./(sqrt(2).*n.*pi.*Rb.*Rb))^2))

All of the variables are constants except Eff and Temp. I would like to calculate values of Eff using Temp between a range of 373 and 623 so that I can plot a graph to investigate the effect of Temp on Eff.

Any Advice would be greatly appreciated

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Answer 1

Chad Greene 2021-3-10

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https://ww2.mathworks.cn/matlabcentral/answers/768552-calculating-values-of-a-dependent-variable-at-a-using-a-range-of-independent-variables#answer_644102

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Welcome to the world of Matlab, Tom.

Indeed, I think this is pretty straightforward. To make a range of values of Temp between 373 and 623, do

Temp = 373:623;

Alternatively, to do the same thing but in steps of 0.1, do

Temp = 373:0.1:623;

Then calculate Eff by

Eff=((Cv.*Temp.*(1-Vr))+(((2.*l.*S.*S)./(n.*n))*((Vi./(pi.*Rb.*Rb))-l))+(M./(R.*Temp))+((Vr^(1-k)).*(R.*Temp./M)))/((Cv.*Temp)+((R.*Temp)./M)+(((S.*Vi)./(sqrt(2).*n.*pi.*Rb.*Rb))^2));

and plot the results like this:

plot(Temp,Eff)

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Chad Greene 2021-3-10

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Ahh, try this. It looks like a few dot operators were missing. My go-to solution when things are acting funny with multiplication, division, or exponents, is to put a dot in front of each one. That seems to have fixed it.

Eff=((Cv.*Temp.*(1-Vr))+(((2.*l.*S.*S)./(n.*n)).*((Vi./(pi.*Rb.*Rb))-l))+(M./(R.*Temp))+((Vr.^(1-k)).*(R.*Temp./M)))./((Cv.*Temp)+((R.*Temp)./M)+(((S.*Vi)./(sqrt(2).*n.*pi.*Rb.*Rb)).^2));