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Path: utzoo!watmath!clyde!floyd!vax135!ukc!dcw
From: dcw@ukc.UUCP (D.C.Wood)
Newsgroups: net.bugs
Subject: Re: Prehistoric BC Bug - (nf)
Message-ID: <4076@ukc.UUCP>
Date: Fri, 3-Feb-84 05:44:41 EST
Article-I.D.: ukc.4076
Posted: Fri Feb  3 05:44:41 1984
Date-Received: Wed, 8-Feb-84 04:30:43 EST
References: <410@umn-cs.UUCP>
Organization: Computing Lab. Kent University, England
Lines: 27

Here is a Bigger and Better Bug in Bc:

scale=99
x=sqrt(2)
x
1.414213562373095048801688724209698078569671875376948073176679737990732\
478462107038850387534327641572
x*x
199999999999999999999999999999999999999999999999999999999999999999999\
9999999999999999999999999999997921066900256462438170679779231122858093\
9665738428702231869954990504493272650132450052758957026311840./
x^2
1.999999999999999999999999999999999999999999999999999999999999999999999\
999999999999999999999999999997

Multiplication can give a relative error of 199(!) orders of magnitude
when the scale is greater than 63.  Is this a record?  Exponetiation gets
it right.

There may still be a bug in another bc library function - I think it was
s() (sine) - which used an undeclared variable `t'.  This caused no problems
unless it was called from a program which also used `t'.

				David Wood

				dcw@ukc.UUCP
				...!vax135!ukc!dcw