Simple Questions, Please Answer 2

hi i'm new and learning about genetic algorithm sample codes

this is part of the code:

for p=1:popsize
   for n=1:nd
      r=rand;
      if r<pm
         new(p,n)=a*old(p,n)*rand;
      else
         new(p,n)=old(p,n);
      end
   end
end

i can't find any old(p,n) function, but it still can run. is old a function provided by the matlab? if so, is there a link to learn about it?

thank you

Answer 1

[per isakson]

old is not the name of a Matlab function. Maybe you have a variable named old

What does

which old 

return?

[Antoni Ho]

function new=ymutr1(old,popsize,nd,pm,a)
    for p=1:popsize
        for n=1:nd
            r=rand;
            if r<pm
                new(p,n)=a*old(p,n)*rand;
            else
                new(p,n)=old(p,n);
            end
        end
    end
end

this is all he wrote, i believe there's no defining old in another file. however, old is also used in another function file, but i'm dead sure, there's no defining code on it

[per isakson]

"this is all he wrote" Not quite. In addition you called the function. old is the first input argument of the function.

[Antoni Ho]

"old is the first input argument of the function."

exactly, so the defining of the old should be in this same file right? but there is none.

[per isakson]

"[...] old should be in this same file right?" No, typically not. Only if ymutr1 is a local or nested function.

The code you showed in a previous comment is that the only content of a file named, ymutr1.m? If so, how did you make this function run? Somewhere there is a call like

out = ymutr1( first_input, second_input, x3, x4, x5 )

in another function or in a script or in the command window. The names of the arguments doesn't matter. See function, Declare function name, inputs, and outputs. old will take the value of first_input.

How did you call ymutr1?