> On 18 Sep 2015, at 16:31, John McKown <john.archie.mck...@gmail.com> wrote: > > On Fri, Sep 18, 2015 at 8:39 AM, John Kane <jrkrid...@inbox.com> wrote: > >> It appears that at least three major spreadsheets, Excel, Apache >> OpenOffice Cal and gnumeric have a problem with the correct order of >> operations when dealing with exponents. The gnumeric result is very strange. >> >> This problem has probably been reported before but just in case it has >> not, it would appear to be one more serious problem with spreadsheets. It >> might be useful in warning people away from using a spreadsheet for serious >> analysis. >> >> Excel >> >> -2^2 = 4 >> >> 2^2^3 = 64 >> >> Apache OpenOffice >> >> -2^2 = 4 >> >> 2^2^3 = 64 >> > > My opinion: One correct, one error! R agrees with me on this: >> 2^2 > [1] 4 >> 2^2^3 > [1] 256 >> 2^(2^3) > [1] 256 >> -2^2 > [1] -4 >> (-2)^2 > [1] 4 >> > > > > >> >> gnumeric # note one correct, one error! >> > > My opinion: two correct! > >
I don’t agree. All are wrong according to standard math rules except Gnumeric with the exponentiation. R is correct. See https://en.wikipedia.org/wiki/Order_of_operations Lesson: always use parentheses to make absolutely clear what you mean. Berend > >> -2^2 = 4 >> >> 2^2^3 = 256 >> >> John Kane >> Kingston ON Canada >> >> > Seems to be a bit off-topic. Unless your point to is to use R for > important work instead of some spreadsheet. A point with which I completely > agree! > > > MS-Excel, and Apache OpenOffice, appear to implement the above as > (2^2)^3==64. Whereas gnumeric implements appears to implement this as: > 2^(2^3)==256. Which is "correct"? Depends on whom you ask. > > ref: https://en.wikipedia.org/wiki/Order_of_operations > <quote> > > If exponentiation is indicated by stacked symbols, the usual rule is to > work from the top down, thus: > [image: a^{b^c} = a^{(b^c)}], > > which typically is not equal to [image: (a^b)^c]. However, some computer > systems may resolve the ambiguous expression differently. For example, > Microsoft > Office Excel <https://en.wikipedia.org/wiki/Microsoft_Office_Excel> > evaluates *a*^*b*^*c* as (*a*^*b*)^*c*, which is opposite of normally > accepted convention of top-down order of execution for exponentiation. If > a=4, p=3, and q=2, [image: a^{p^q}] is evaluated to 4096 in Microsoft Excel > 2013, the same as [image: (a^p)^q]. The expression [image: a^{(p^q)}], on > the other hand, results in 262144 using the same program. > </quote> > > Gnumeric abides by the above definition. FWIW. BTW - MS-Excel also has > 1900 as a friggin' leap year (due to Lotus 1-2-3 apparently), so I don't > consider MS-Excel (or anything else from MS for that matter) to be a > definitive source of correctness. Personal opinion. FSF associate member. > Penguinista. > > -- > > Schrodinger's backup: The condition of any backup is unknown until a > restore is attempted. > > Yoda of Borg, we are. Futile, resistance is, yes. Assimilated, you will be. > > He's about as useful as a wax frying pan. > > 10 to the 12th power microphones = 1 Megaphone > > Maranatha! <>< > John McKown > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
