Although I agree with most of what Denker has said on this topic, I take
some offense at his statement "...[division by subtraction] as a
practical algorithm it is laughable..."
I have stated I have used division by subtraction in some
assembly-language programming, and John's statement could be construed
that I was pretty stupid to do so.
If you don't know what the programmer was programming; if you don't know
whether instruction space or register limitations were bigger concerns
than timing; if you don't know whether the programmer knew there would
be a limited range of dividends and divisors... basically speaking, if
you weren't in his shoes... then it seems out of place to say what he
did was laughable.
As an assembly-language programmer I had a pretty big bag of tricks.
Division by subtraction was in the bag. Sometimes it was appropriate
and sometimes it was not. Some of the tricks were so cool they made me
smile, but none was laughable.
Michael D. Edmiston, Ph.D.
Professor of Physics and Chemistry
Bluffton University
Bluffton, OH 45817
(419)-358-3270
edmiston@bluffton.edu