Myke Predko wrote:

> Quick question for the Math Wizzes out there.

  Sorry, pass!

> Is there a series method of doing a divide by a constant?  I'm
> thinking of the divide by three operation:
> n/3 = x/2 - x/4 + x/8 - x/16 + x/32 - x/64...

  From the last thread on this subject, you mean?

> which is very easy to code and is very fast.

  OK, so what's the problem then?  This approach is better described as
the "multiply by 1/3" operation, and it absolutely general.  IOW, for
each division, you determine the recurring binary expansion of the
fraction, and code that.

>  Of course, powers of two work the same way.

  You mean, they only have one term.

> Is there a general case for non-powers of two?

  Yep.  But it eludes me right at the moment.  I have to go on a 400 km
and return trip today.

> I got asked for a routine which needs a divide by seven and wondered
> if there was a better way of doing it instead of the methods which use
> a variable.

  What methods are they?  Do you mean better than the above method?  I
don't think so, it is pretty accurate.

  What was determined on the last round is that you have to be *very*
careful not to lose precision during the summing operation.
--
  Cheers,
        Paul B.