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From: johnl@haddock.UUCP
Newsgroups: net.lang
Subject: Re: Implementation of scientific functio - (nf)
Message-ID: <184@haddock.UUCP>
Date: Tue, 12-Jun-84 23:37:15 EDT
Article-I.D.: haddock.184
Posted: Tue Jun 12 23:37:15 1984
Date-Received: Thu, 14-Jun-84 00:25:12 EDT
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#R:sdccsu3:-190500:haddock:12300003:000:641
haddock!johnl    Jun  9 19:41:00 1984

People have been studying numerical algorithms for a long time,
and there are many references that you could look up.  For most
transcendental functions, the usual approach is to precondition
the arguments and check for special cases, and then compute a
polynomial which approximates the desired function. Look at the
sources for the C math library where there are comments referring
you back to their origins both to see some algorithms and get the
name of the source book they used.

In the particular case of square root, Newton's method provides an
interative method which converges in log2(wordsize), i.e. fast.

John Levine, ima!johnl