Daniel Lakeland wrote:
> Fixed point extrapolation is probably relatively easy to put an error
> bound on though when compared with discrete logarithm approximations
> and soforth.
It seems, that storing log with 8 bit precision is enough, to
compute dew point with a resolution of 0.1K - the problem is very
good-natured. (The formula itself is an approximation of a series
of physical measurement and not a theoretical result.)
Dew point is only a vehicle for me, to get more clearity about
fixedpoint computations on ?Cs.
It seems to me, that there are two general strategies to solve
the problem:
- Lookup tables and optional interpolation, if not enough
memory is available to store the full table.
- Using an integer formula and implement it in a way, that
balances subexpressions to minimize distortions.
The first is more general, but more expensive to realize, while
the second can be done quite easy, if it is possible - simply
manipulate an integer expression.
If the error estimation can be done in some generalized way, I
would prefer the second strategy. For known sensor resolutions,
it can be done using the brute force method.
On the other hand, the lookup table approach might be a good
candidate to build a generator, that eats a formula and generates
the table and a (C-) function to query it - maxima is a good
vehicle to implement such a generator.