[net.wanted] need fast algorithm for reciprocal

geoff@burl.UUCP (geoff) (06/12/84)

I am working on a very primitive machine which lacks a division
operation.  What I really need is a reciprocal, so either type
algorithm would be fine.  I have shift, +,-, and *, as well as
logical operators, available.  I recall that IBM had an algorithm
many years ago which used multiplication to divide (sort of a binary
search -- multiply guess * number, compare to 1, adjust guess), but
I don't remember it well enough (my attempt at such an algorithm
required an avg of 20 iterations for reciprocals of numbers between 2
and 8000).

Any help from the net would be sincerely appreciated.

	thanks,
		geoff sherwood
		burl!geoff

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