get series precision

[John Jones <jj@asu.edu>]

Hi,

If I have a power series, is there a function which tells me its 
precision?  For example,

f1 = exp(x)
f2 = (f1-1)/x

With the default, f1 is +O(x^17) and f2 is +O(x^16).  How can a script 
tell which is which?

John