Calculate complicated integral many time

Hello every body. I am trying to integrade a complicated function but with command int, it takes for ever.My code is:

syms x z th1;
y=0;
r=(x^2 + y^2 + z^2)^0.5;
th=acos(z/r);
fh=atan(y/x);
d=2;
a=1;
d1=(a^2)/d;
L=1.5;
R1=(r^2 + d^2 - 2*r*d*(cos(th)*cos(th1) + sin(th)*sin(th1)))^0.5;
R2=(r^2 + d1^2 - 2*r*d1*(cos(th)*cos(th1) + sin(th)*sin(th1)))^0.5;
F1=d/R1;
F2=-(a/R2);
f=F1+F2;
int(f,th1,-L/d,L/d)

I want to compute it and then take the gradient of that.But as long as i wait it does nothing. I dont know anything about matlab, i just need the result.It is very important to calculate it because without it i cant do nothing. I have also have to use surface function,contour function in the above result. Thanks in advance