Question

I am trying to figure out why I am getting all zeros back in the code below.

a = 7.0e16;
e = 100000;
r = 8.3140;
t = 253:2:325;

k = a.*exp(-e./t.*r);

k returns as 1×37 array consisting of only zeros.

Is it because my numbers are too large or too small?

Answer 1

You are getting underflow. Things become zero in the exp, and multiplying by a big number afterwards is too late. It looks like a physics equation – in which case you want to divide by r, not multiply.
Try

exp(log(a)-e./(t*r))

It should work

EDIT – have to add, not multiply, log(a) in the exponent…