Rounding problem R vs Excel
Hi: Below you find two articles about Excel. Knusel, L. (1998) On the Accuracy of Statistical Distributions in Microsoft Excel 97. Computational Statistics & Data Analysis. Vol. 26, No. 3, pp. 375-377 McCullough, B.D. y Wilson, D. (1999) On the Accuracy of Statistical Procedures in Microsoft Excel 97. Computational Statistics & Data Analysis. Vol. 31, No. 1, pp. 27-37
On Wed, 4 Jun 2003, Paul, David A wrote:
I don't have the reference, but a biologist friend of mine once showed me a refereed journal article that purported to demonstrate numerical errors made by MSExcel. This would have been Excel97 or Excel2000... In any case, the journal's scope was biological in nature and the article was of interest since Excel is heavily used in that community. -david paul -----Original Message----- From: Duncan Murdoch [mailto:dmurdoch at pair.com] Sent: Wednesday, June 04, 2003 8:34 AM To: MSchwartz at medanalytics.com Cc: R-help at stat.math.ethz.ch Subject: Re: [R] Rounding problem R vs Excel On 04 Jun 2003 00:24:08 -0500, you wrote:
Excel 2002 (XP): Cell Formula Value = 0.5 - 0.4 - 0.1 0.00000000000000000000E+00 =(0.5 - 0.4 - 0.1) -2.77555756156289000000E-17
...
What is interesting is the change in the displayed value in Excel when the second formula is surrounded by parens (which I found purely by accident). This would suggest that there may be something going on in the parsing of the cell formula that affects the calculation and displayed value.
"Interesting"? I'd say "horrifying". When (expr) does not evaluate the same as expr, what can you trust? Duncan Murdoch
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