>
>  The equation is:  1/T = a + b(ln R) + c(ln R)^3  where T is in Kelvin,
>  a,b, and c are the coefficients provided by the manufacturer, R is the
>  resistance in ohms, and the notation "ln" is the natural logarithm
>  (base e).  I assume the "cubed" term can be done by doing three
>  "multiplies" but I don't know about the log and the reciprocal.

And if you don't want to use linear interpolation, go to a good library and
look for a mathematical reference book. There are several ways of
'developing' logarithms and the inverse into sums of products. I don't want
to type them all, since they contain exponents and (constant) divisions,
and depending on the range (and acceptable pre- and post-conversion) you
can get different formulas.
Just an e.g. (from Bronstein-Semendjajew: Taschenbuch der Mathematik):

(1+x)^-m = 1 - mx + (m*(m+1))/2!*x^2 - .....  substitutes easily for 1/T (=T^-1)
and one development for ln x (for 0 < x <= 2, which can be achieved by a
simple multipllication in your case):
ln x = (x-1) - (x-1)^2/2 + (x-1)^3/3 - (x-1)^4/4 ....

I admit, a lookup-table and some linear interpolation might be easier (and
probably is the more usual way of doing these things), but above can be as
accurate as you want it with less memory 9and more calculating time).

Bye
  Markus

P.S. No, I haven't actually tried to implement this in a uP (yet !).