what's my error in this code? Unrecognized function or variable 'integrator'.

Unrecognized function or variable 'integrator'.

can anyone guide me to solve this error!?

format long
clear all
f = @(x) x^5*exp(-x)*cos(sqrt(x));   %Sample function
integrator(f,[1.008 10.04],1e-6)

%Main function
function integrator(f,t,er) 
h=0.01; 
n=abs(t(2)-t(1))/h;
cnt = 0;
prev = 0; 
func(prev,f,t,h,n,cnt)

    function func(prev,f,t,h,n,cnt ) %sub function 
        tic
        cnt = cnt + 1;
        %Simpson integration rule 
        I=(f(t(2))+f(t(1)));
        for j = 1:2:n-1
            I=I+4*f(t(1)+j*h);
            
        end
        for k = 2:2:n-2
            I=I+ 2*f(t(1)+k*h);
        end
        answerS = I*(h/3) ;
        
        if(abs(prev - answerS)<0.1*er && cnt>1) 
            fprintf('Integral is: %f\n',answerS)
            fprintf('Total number of iterations taken: %d\n',cnt)
            
            return 
        elseif(cnt>100)
            fprintf('Recursion depth More than 100!!!\n') 
            fprintf('Integral is: %f\n',answerS)
            return
        else
            time = toc;
            if(time >= 5*60*60)
                fprintf('Compplex function!!!! Execution time more than 5 minutes\n!!!!')
                return
            end
            func(answerS,f,t,h/2,2*n,cnt) %Recurssion
        end
    end
return

end

[Walter Roberson]

The code works when I test it (or at least it does not fail in the way you describe)

If you are using R2015a or earlier, then you need to ensure that your function integrator is in a file named integrator.m . If you are using R2015b or later then function integrator can be in the same file as your script that calls it, as long as the script is not named integrator