I just wrote:

> > [Quoting Doug Manzer:]
> > One thing I would try here is to multiply a & b by 1000 so that
> > the result Y would ends up 1000 times its actual value y. If the
> > smallest non-zero displayable value y = 0.001 then Y = 1; for the
> > largest y = 9999, Y = 9,999,000 which is expressable with 24 bits;
> > this would require the 32-bit f/p library. AN575 does have a
> > conversion for f/p to integer which I could then convert to BCD
> > fairly easily. A range check would determine where the decimal
> > point belonged. However, if there's an easier way to do this I'd
> > appreciate hearing about it -- surely this must be a common
> > application for the PIC.
>
>     If those user-settable constants are entered via the 4-digit LCD
>     display, I would dump the floating-point routines completely and
>     do all the calculations with integer math, adjusting the decimal
>     point as needed. This sounds pretty much like what you're
>     suggesting.

Doug:

I should have elaborated a little:  I would NOT multiply "a" and "b"
by 1000 before performing the calculations; I'd simply ignore the
decimal points and treat "a" and "b" as integers in the range
[1-9999] ("x", of course, would remain an integer in the range
[0-255]).

After performing the (now greatly-simplified) multiplication and
addition, I'd set "y"'s decimal point based on the original
decimal-point positions of "a" and "b".

-Andy

Andrew Warren - fastfwd@ix.netcom.com
Fast Forward Engineering, Vista, California
http://www.geocities.com/SiliconValley/2499