how to minimize a function using Genetic Algorithm in matlab

I have the following code with function Y = 1000*log(1+4.5/((100-u*cos(theta)*(X))^2+(100+u*sin(theta)*X-4.9*...

(X)^2)^2));

I want to minimize this using GA optimtool. How could I do this because my function is calculated in a loop. So, how could I use the whole code as fitness function?

a = 0;

b = 6;

B = 1000;

u = 40;

theta = pi/12;

Int_simp = zeros(1,10);

disp(Int_simp);

for N = 1:10

sum_simp = 0;

dx=(b-a)/N;

for r = 1:N

X = a + ((r-1)*dx);

Y = 1000*log(1+4.5/((100-u*cos(theta)*(X))^2+(100+u*sin(theta)*X-4.9*...

(X)^2)^2));

if (mod(r,2) == 0)

coeff = 4;

else

coeff = 2;

end

if (r == 0)||(r == N)

coeff = 1;

end

sum_simp = sum_simp + (coeff*Y*dx*(1/3));

end

Int_simp(N) = sum_simp;

end

plot(Int_simp,'-sm');