Problem with a program concerning composite trapezoid rule

In this program I'm using the composite trapezoid rule on the function in my program. I've used the same program with different functions and haven't had issues till I tried it with this function. (Not sure if I'm using the dots correctly in my function) It says I have an error with line S=f(a); Here is code:

f = @(x) -exp(-(ln(t).^2))*(1./t);
a = 1;
b = 0; 

n= 10000;
format long
h = (b-a)/n;
S = f(a);
i=1:1:n-1;
x=a+h*i;
y=f(x);
S=S+2*sum(y);
S=S+f(b);
F=h*S/2