I am not well verse in Matlab, and tried to run the code below. However, I keep getting an error stating "Not enough input arguments." I'm not sure what does this means.

Question

shunmugam hemalatha 2021-5-31

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https://ww2.mathworks.cn/matlabcentral/answers/844155-i-am-not-well-verse-in-matlab-and-tried-to-run-the-code-below-however-i-keep-getting-an-error-sta

回答： shunmugam hemalatha 2021-6-2

clear all
c0 =40;
cd = 50;
y0 = 0.09;
h = 0.7;
tow = 5;
u = 0.05;
a = 260;
b = 0.1;
syms T tow
%x = '((a*h)/2)+((a*tow*T)/3)+((a*h*T*((exp^(-u*tow))+b))/3)+((a*tow*(T^2)*((exp^(-u*tow))+b))/8)-(c0/(T^2))+(cd*((3*a*y0*(exp^(-u*tow)))-(2*T*a*b*y0*(exp^(-u*tow)))-(2*T*a*(b^2)))/6)';
%y ='1-((u*a*h*(T^2)*y0*(exp^(-u*tow)))/6)-((u*a*tow*(T^3)*y0*(exp^(-u*tow)))/24)-(cd*u*T*y0*(exp^(-u*tow))*((3*a-a*b*T)/6))';
%[T, tow]= solve ([x, y])
[solT,soltow] = solve ([((a*h)/2)+((a*tow*T)/3)+((a*h*T*((exp^(-u*tow))+b))/3)+((a*tow*(T^2)*((exp^(-u*tow))+b))/8)-(c0/(T^2))+(cd*((3*a*y0*(exp^(-u*tow)))-(2*T*a*b*y0*(exp^(-u*tow)))-(2*T*a*(b^2)))/6)==0, 1-((u*a*h*(T^2)*y0*(exp^(-u*tow)))/6)-((u*a*tow*(T^3)*y0*(exp^(-u*tow)))/24)-(cd*u*T*y0*(exp^(-u*tow))*((3*a-a*b*T)/6))==0], [T, tow]) 
TC = (c0/T)+(1/T)*(((a*h*(T^2))/2)+((a*tow*(T^3))/6)+((((a*y0*(exp^(-u*tow))+b)/2)*((h*(T^3)/3)+((tow*(T^4)/12))))))+(cd/T)*((((T^2)*y0*(exp^(-u*tow)))*(3*a-a*b*T))/6)+((tow*T)/T) 

I need the answer: TC =230.390, T = 0.388 and tow = 48.420. Help me to find the answer.

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Answer 1

Walter Roberson 2021-5-31

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在 MATLAB Online 中打开

In order to use

exp^(-u*tow)

You would need to have defined exp as a square array (including a scalar), or you would have had to have defined exp as a function that accepted no arguments.

If you were expecting exp to be the exponential, then do not use ^ : use

exp(-u*tow)

You could instead use

exp = exp(1);

and continue to use exp^ ... but that is not recommended, and would be less accurate than using exp() without the ^

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shunmugam hemalatha 2021-5-31

I agree your suggestion. That is by using exp() without the ^.

But I'm getting the answer like this

-0.0029562989695424121250461283911032

TC = tow + (((117*exp(-tow/20))/10 + 1/20)*((tow*T^4)/12 + (7*T^3)/30) + (130*T^3*tow)/3 + 91*T^2)/T + 40/T - (3*T*exp(-tow/20)*(26*T - 780))/4

Is there any mistake in coding. kindly, help me.

Walter Roberson 2021-5-31

在 MATLAB Online 中打开

c0 =40;

cd = 50;

y0 = 0.09;

h = 0.7;

tow = 5;

u = 0.05;

a = 260;

b = 0.1;

syms T tow

[solT,soltow] = solve ([((a*h)/2)+((a*tow*T)/3)+((a*h*T*((exp(-u*tow))+b))/3)+((a*tow*(T^2)*((exp(-u*tow))+b))/8)-(c0/(T^2))+(cd*((3*a*y0*(exp(-u*tow)))-(2*T*a*b*y0*(exp(-u*tow)))-(2*T*a*(b^2)))/6)==0, 1-((u*a*h*(T^2)*y0*(exp(-u*tow)))/6)-((u*a*tow*(T^3)*y0*(exp(-u*tow)))/24)-(cd*u*T*y0*(exp(-u*tow))*((3*a-a*b*T)/6))==0], [T, tow])

Warning: Unable to solve symbolically. Returning a numeric solution using vpasolve.

solT =

34.643023131338585589918914754588

soltow =

TC = (c0/T)+(1/T)*(((a*h*(T^2))/2)+((a*tow*(T^3))/6)+((((a*y0*(exp(-u*tow))+b)/2)*((h*(T^3)/3)+((tow*(T^4)/12))))))+(cd/T)*((((T^2)*y0*(exp(-u*tow)))*(3*a-a*b*T))/6)+((tow*T)/T)

TC =

subs(TC, [T, tow], [solT, soltow])

ans =

3033.4109097492696411973724961761

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