Error with function handle while running Genetic Algorithm code

Hello! I wrote the following code in Matlab trying to solve a problem using Genetic Algorithms. When it runs it gives me these errors:

Error using functionHandleOrCell (line 12)

The constraint function must be a function handle.

Error in validate (line 228)

[nonlcon,NonconFcnArgs] = functionHandleOrCell('NonconFcn',nonlcon);

Error in gacommon (line 65)

[options,nvars,FitnessFcn,NonconFcn] = validate(options,type,nvars,fun,nonlcon,user_options);

Error in ga (line 336)

NonconFcn,options,Iterate,type] = gacommon(nvars,fun,Aineq,bineq,Aeq,beq,lb,ub, ...

Error in eqga (line 23)

[x,fval,reason,output] = ga(FitnessFcn,numberOfVariables,[],[],[],[],lb,ub,options);

clc; 
 
type create_population.m 
type crossover.m 
type mutate.m 
type fitness.m 
type plot_it.m 

lb=0;
ub=2;
FitnessFcn = @(x) eq_fitness(x); 
my_plot = @(options,state,flag) plot_it (options,state,flag,x);
options = optimoptions('ga','PopulationType', 'custom', ...
                            'InitialPopulationRange', [0;2]);
options = optimoptions('ga', options, ...
                            'CreationFcn', @create_population, ...
                            'CrossoverFcn', @crossover, ...
                            'MutationFcn', @emutate, ...      
                            'PlotFcn', my_plot, ...
                            'Generations',2000,'PopulationSize', 100, ...
                            'StallGenLimit',400, 'Vectorized', 'on');
numberOfVariables=1;							
[x,fval,reason,output] = ga(FitnessFcn,numberOfVariables,[],[],[],[],lb,ub,options);

But when I take out the options at [x,fval,reason,output] it works fine and it gives me the result I want.

I don't know what's wrong. Is there any mistake in this code? Or there might be mistake in the functions for crossover, mutataion etc?

[Jan]

What is x here:

my_plot = @(options,state,flag) plot_it (options,state,flag,x);

[Nick]

x is the solution to the problem

Answer 1

[Steven Lord]

According to the documentation for the ga function you could be trying to call one of these syntaxes (ignoring the number of ourput arguments for now):

x = ga(fun,nvars,A,b,Aeq,beq,lb,ub,nonlcon)
x = ga(fun,nvars,A,b,Aeq,beq,lb,ub,nonlcon,options)
x = ga(fun,nvars,A,b,[],[],lb,ub,nonlcon,IntCon)
x = ga(fun,nvars,A,b,[],[],lb,ub,nonlcon,IntCon,options)

Your call was (again ignoring outputs):

ga(FitnessFcn,numberOfVariables,[],[],[],[],lb,ub,options);

So A is [], b is [], Aeq is [], beq is [], lb is lb and ub is up. Now in all these syntaxes the next input is the nonlinear constraint function nonlcon. But options is not a nonlinear constraint function.

To solve the problem:

If you want to use the second of those syntaxes I copied from the doc, put a [] between ub and options.

If you want to use the fourth, put [] and an IntCon vector.

[Nick]

I did write

A=[];
b=[];
Aeq=[];
beq=[];
nonlcon=[];						
[x,fval,reason,output]= ga(FitnessFcn,numberOfVariables,A,b,Aeq,beq,lb,ub,nonlcon,options)

But now I have these errors:

Error in fitness (line 4)

scores=abs(x^2+sqrt(x^2+1)-2);

Error in eqga>@(x)eq_fitness(x)

Error in createAnonymousFcn>@(x)fcn(x,FcnArgs{:}) (line 11)

fcn_handle = @(x) fcn(x,FcnArgs{:});

Error in makeState (line 64)

Score = FitnessFcn(state.Population(initScoreProvided+1:end,:));

Error in gaunc (line 40)

state = makeState(GenomeLength,FitnessFcn,Iterate,output.problemtype,options);

Error in ga (line 371)

[x,fval,exitFlag,output,population,scores] = gaunc(FitnessFcn,nvars, ...

Error in eqga (line 28)

[x,fval,reason,output]= ga(FitnessFcn,numberOfVariables,A,b,Aeq,beq,lb,ub,nonlcon,options)

[Steven Lord]

That doesn't look like the whole error message. I expect there were some lines displayed in red and/or orange before the "Error in fitness (line 4)" line that you copied and pasted. Those lines will be useful in determining what's going on.

I suspect I know the problem but those additional lines would confirm or disprove my suspicion.

[Nick]

That's true! I thought the orange ones were not so important. Here is the whole error message: What do you think is the problem?

Warning: All constraints are ignored for 'custom' population.

> In gacommon (line 42)

In ga (line 336)

In eqga (line 28)

Undefined operator '^' for input arguments of type 'cell'.

Error in fitness (line 4)

scores=abs(x^2+sqrt(x^2+1)-2);

Error in eqga>@(x)fitness(x)

Error in createAnonymousFcn>@(x)fcn(x,FcnArgs{:}) (line 11)

fcn_handle = @(x) fcn(x,FcnArgs{:});

Error in makeState (line 64)

Score = FitnessFcn(state.Population(initScoreProvided+1:end,:));

Error in gaunc (line 40)

state = makeState(GenomeLength,FitnessFcn,Iterate,output.problemtype,options);

Error in ga (line 371)

[x,fval,exitFlag,output,population,scores] = gaunc(FitnessFcn,nvars, ...

Error in eqga (line 28)

[x,fval,reason,output]= ga(FitnessFcn,numberOfVariables,A,b,Aeq,beq,lb,ub,nonlcon,options)