Undefined variable in functions

Following is the file simplefitnes.m

 function y = simple_fitnes(x)
  y = p * (x(1)^2 - x(2)) ^2 + (1 - x(1))^2;
end

The file below is abc.m

 FitnessFunction = @simple_fitnes;
p = input('p')
numberOfVariables = 2;
[x,fval] = ga(FitnessFunction,numberOfVariables)

When I run abc.m get an error "Undefined function or variable p. What is the error I am making? How to rectify it?

Answer 1

[Star Strider]

You have to pass ‘p’ as a variable to your ‘simple_fitnes’ function. To do that, you first have to add it as an input argument to ‘simple_fitnes’, and then create the function handle for ‘simple_fitnes’ that passes ‘p’ to it, but is ‘invisible’ to the ga function.

This does exactly that:

function y = simple_fitnes(x,p)
y = p * (x(1)^2 - x(2)) ^2 + (1 - x(1))^2;
end

p = input('p = ')
FitnessFunction = @(x)simple_fitnes(x,p);
numberOfVariables = 2;
[x,fval] = ga(FitnessFunction,numberOfVariables)

See the documentation on Anonymous Functions in Function Basics for details on how the anonymous function call works here.