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Undefined function or variable error even though function is saved

Asked by Harvey Rael on 18 May 2018 at 2:49
Latest activity Answered by Harvey Rael on 18 May 2018 at 14:06

Keep getting the message "undefined function or variable"..I'm trying to create this function to pass to a genetic algorithm to optimise for three variables (k1,k2,k3) but even when I test it I get an error. It saves as a .m file though. What's going wrong?

function y = newFitness(k)
% Define constants
AU = astroConstants(2);
mu = astroConstants(4);
% Define start and finish parameters for the exponential sinusoid.
r1  = AU;                 % Initial radius
psi = pi/2;               % Final polar angle of Mars/finish transfer
phi = pi/2;
theta_dot = sqrt( mu/(((r1/exp(k(1)*sin(phi)))*exp((k(1)*sin(k(2)*(psi + 2*pi*k(3))+phi))))^3) * 1/(tan(atan(k(1)*k(2)*cos(k(2)*(psi + 2*pi*k(3))+phi)))^2 + k(1)*k(2)^2*sin(k(2)*(psi + 2*pi*k(3))+phi) +1) );
y = theta_dot - 94608000;

Edit: Following on from one of the suggestions below, there arises the following information : The function can be found apparently.

    which newFitness
Y:\MATLAB\newFitness.m

So here is the genetic algorithm code that I am trying to pass it on to. I'm not sure why that is important, because before I even touch the GA code, I try and test my function by typing :

    newFitness([1 2 3])

Which still gives me an error message of "Undefined function or variable 'newFitness'". But here's the GA code anyways.

clc;clear;
objective_function = @newFitness;
nvars = 3;
[k,fval]=ga(objective_function,nvars);

  6 Comments

To answer your questions (and thank you for the speedy responses!).

  1. It is on my path.
  2. Astro Constants is defined properly, and the AstroConstants function is on my path also. I don't know what you mean by passing k1,k2,k3 in an array, I watched a YouTube video on getting a fitness function for multiple variables, and that is what he did, so I copied that.
  3. The error message is "Undefined function or variable 'newFitness'" which occurs whether I try to pass it to the GA or if I just try and test the function on its own. But it saves fine.

Harvey - is the newFitness function in the MATLAB search path? In the command window, type

 which newFitness

to see if the function can be found. If not, then add it to the search path. If it can be found, then there might be something wrong with the code that is trying to pass this function to the GA...so please copy and paste that code (which is throwing the error) to your question.

Geoff - See the edit on the question. Hope that helps.

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1 Answer

Answer by Harvey Rael on 18 May 2018 at 14:06
 Accepted Answer

*Update* : MATLAB is a cruel mistress. I turned off my computer last night after many attempts (and after asking this question) when nothing worked. Turned it on again this morning without touching any code at all.. it works enough to give me answers. I don't know why, all paths are the same. Now I just need to provided constraints..

Thanks for all your help!

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