On 5/19/09 1:57 PM, "Igor Tandetnik" <itandet...@mvps.org> wrote:
> "John Machin" <sjmac...@lexicon.net> wrote > in message news:4a129cb4.2090...@lexicon.net >> It's handy for checking how things work e.g. >> >> sqlite> select (-1) % 7; >> -1 >> sqlite> -- it's not a real modulo operator :-( > > What do you feel is wrong with this result? What should a "real" modulo > operator return, in your opinion? Before you answer, note that you very > likely want this equality to hold for all a, b!=0 : > > a = q*b + r > where q = a/b, r = a%b > > Igor Tanetnik > My math courses taught me a long time ago, that the remainder r in Euclidian division of a by b is defined by: There exists unique natural numbers q and r such as: a = b*q+r 0 <= r < b q is defined as the quotient, r is defined as the remainder. So if the % operator wants to match that math definition, its results should never be negative. In the example given, (-1)%7 should therefore be 6. But I will not argue that the % operator needs to match the math definition, though I would probably prefer it to. Jean-Denis _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
