Path: utzoo!attcan!utgpu!watmath!att!tut.cis.ohio-state.edu!mailrus!wasatch!cs.utexas.edu!ut-emx!bill
From: bill@ut-emx.UUCP (Bill Jefferys)
Newsgroups: comp.sys.mac
Subject: Re: Bug in EXCEL v. 2.2, and a flame
Message-ID: <16863@ut-emx.UUCP>
Date: 10 Aug 89 05:54:37 GMT
References:  <1989Aug1.193850.4999@mdivax1.uucp>
Reply-To: bill@emx.UUCP (Bill Jefferys)
Organization: UTexas Computation Center, Austin, Texas
Lines: 38

In article <1989Aug1.193850.4999@mdivax1.uucp> hiebert@mdivax1.uucp (Graeme Hiebert) writes:
#In article  jk3t+@andrew.cmu.edu (Jonathan King) writes:
#> 
#> Interesting.  My calculator (a Sharp EL-512 II) gives virtually the same
#> erroneous square root as Excel!  That is, the square root of .999975 is
#> given as .999987499.  It looks like this problem is not unique to Excel;
#> to make its way into the entirely silicon brain of my calculator this error
#> must be the result of an ancient and honorable (although badly conditioned)
#> numerics routine...
#> 
#> jking
#
#Very interesting indeed.  My Sun gives
#        sqrt(0.9999750000000000000000000) = 0.9999874999218740234222409
#and
#        0.9999749992187 * 0.9999749992187 = 0.9999499990624
               ^[insert 8 here]  ^[insert 8 here]

#Now, let's see, if I do the multiplication by hand, I get

[long, irrelevant calculation omitted]

#   0.99994999906243906561042969
#   ^^^^^^^^^^^^^^^
#   Well look at that.  My Sun multiplies the same way I do.  Shame on us.

Shame on me. I mistyped the number Excel gave, leaving out the "8". There
IS bug in Excel, however. I apologize to everyone on the net for my typo, 
which has caused great confusion. 

I have received mail from Microsoft, acknowledging the bug, and
saying that they have located and fixed it. I hope the the corrected
version will be made available for those with older machines soon.

Also, I want to thank all those who helped to attract Microsoft's 
attention to my plea.

Bill Jefferys