Error: Invalid expression. When calling a function or indexing a variable, use parentheses. Otherwise, check for mismatched delimiters.

I am trying to run this code but it gives me a lot of error.

function vi=successor(optimValues, ~)  
    
%get current state, which is automatically put in optimValues
   xi = optimValues.x;   
   nVar = length(xi);
   lb=-5.12;
   ub=5.12;
%Choose a random solution xk. Next solution will be shifted towards xk in the neighbourhood of xi
 
   xk=GenerateRandomSolution(nVar,lb,ub);
      
   % choose a random dimension j to vector xk = the next solution vi will only be on dimension j direction in the neighbourhood   
   j= randi([1 nVar]);
       
 % define neighbourhood coefficient and choose a random coefficient in neighbourhood size [-1 1]
   q=1;                    % Neighbourhood diameter upper bound
   phi=q*unifrnd(-1,+1);
   
  % generate a new successor vi 
  vi=xi;
  vi(j)=xi(j)+phi.*(xi(j)-xk(j));
  if vi(j)>ub
      vi(j)=ub;
  elseif vi(j)<lb
      vi(j)=lb;
  end
 
end

and Error code is below:

>> successor(optimValues, ~)

successor(optimValues, ~)

↑

Error: Invalid expression. When calling a function or indexing a variable, use parentheses. Otherwise, check for

mismatched delimiters.

Please tell me how I can get past this.

thanks

[Walter Roberson]

 successor(optimValues)

Or

 successor(optimValues, [] )

[Gizen Mutlu]

When I tried

successor(optimValues)

I get this error;

Not enough input arguments.

Error in successor (line 4)

xi = optimValues.x;

but is curret state getting automatically in optimValues?

Answer 1

[Walter Roberson]

You would get the error about not enough input arguments on the line

   xi = optimValues.x;

under the circumstance that the optimValues you passed in is a function handle that needs at least one argument, and you are running R2019b or later.

Answer 2

[Siriniharika Katukam]

Hi

Since you are using optimValues.x, optimValues must support dot indexing. The error in line 4 usually arise when optimValues.x is not initialized in optimValues. This means, may be your input optimValues is just a scalar.

[Walter Roberson]

No, if the object does not supprot dot indexing you get

Dot indexing is not supported for variables of this type.