Function handle doesn't work as intended
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Karsten Gros
on 15 Jun 2017
Commented: Karsten Gros
on 28 Jun 2017
Hi, I have a question regarding my matlab-code. Basically, the code should calculate the heat-transfer for drop-wise condensation. At the end of the program, I should have a funvtion with deltaT as variable parameter. But the error-message basically says that .* can't be used with function handles. I attached the file, so if anyone is willing to help me, you would make me very happy :) Any ideas how I could get the program fixed? Thanks in advance and best regards, Karsten
2 Comments
James Tursa
on 15 Jun 2017
Please copy and paste the entire error message so we know which exact line is causing the problem and which exact error message MATLAB is giving you.
Accepted Answer
Walter Roberson
on 15 Jun 2017
Q = @(r, deltaT) pi.*r.^2.*(deltaT-(2.*T_sat.*sigma)./(H_fg.*r.*rho_l)).*((1+cos(Theta)./(2.*h_i)+delta./(lamda_coat.*sin(Theta).^2)+(r.*Theta)./(4.*lamda_l.*sin(Theta)))).^(-1)
needs to be
Q = @(r, deltaT) pi.*r.^2.*(deltaT-(2.*T_sat.*sigma)./(H_fg.*r.*rho_l)).*((1+cos(Theta)./(2.*h_i(deltaT))+delta./(lamda_coat.*sin(Theta).^2)+(r.*Theta)./(4.*lamda_l.*sin(Theta)))).^(-1)
4 Comments
Walter Roberson
on 17 Jun 2017
When that change is made, that error message disappears, leaving you with other error messages.
- You use delta_T twice in one of the lines, instead of deltaT
- You use r once in a line where r has not been defined; it appears that should be r_c which is used multiple times on that line
- You call upon ln() instead of log() . That is not an uncommon error -- and yet when I research I have been unable to find any major programming language that calls it ln()
Revised code attached. I have no idea if the correct value is calculated.
James Tursa
on 19 Jun 2017
Not a "major programming language", but MS Excel uses ln() for natural log.
More Answers (2)
James Tursa
on 15 Jun 2017
Just quickly looking though what was posted, this line:
grid onq_tot2 = @(deltaT) integral(@(r) stopp(r), r_c, r_max)
looks like it should be two separate lines:
grid on
q_tot2 = @(deltaT) integral(@(r) stopp(r), r_c, r_max)
0 Comments
Karsten Gros
on 19 Jun 2017
Edited: Karsten Gros
on 19 Jun 2017
8 Comments
Walter Roberson
on 28 Jun 2017
No, you have not defined dT for that last line. Is there a reason you changed it from
q_tot = @(deltaT) q_tot1(deltaT)+q_tot2(deltaT);
Variable names do NOT need to match in the calling function and the called function! Variable names need to be consistent within any one function.
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