On Wed, Jul 9, 2008 at 7:29 AM, Gabriel Dos Reis wrote: > On Wed, Jul 9, 2008 at 12:35 AM, Bill Page wrote: > >> *yixin.cao wrote:* -- In the light of polynomial, (2d) is a >> non-zero polynomial, so that it's always safe to write (1/(2d)) >> >> If a value of 0 is subsituted for d in this "non-zero polynomial" >> then in what sense is '1/(2d)' safe? > > This is the classical difference between a function (defined by a > polynomial) and a polynomial. > > There is no doubt that -- if d is the unknown -- then 2d is a non-zero > polynomial and as such has an inverse in the field Q(d). >
But is computing in the field Q(d) "safe" if we eventually intend to replace d with some non-symbolic value? Isn't there a possibility that such computations could lead to incorrect results due to (for example) implicit divisions by 0? It seems to me that an inverse in Q(d) might have no counterpart in Q. Regards, Bill Page. ------------------------------------------------------------------------- Sponsored by: SourceForge.net Community Choice Awards: VOTE NOW! Studies have shown that voting for your favorite open source project, along with a healthy diet, reduces your potential for chronic lameness and boredom. Vote Now at http://www.sourceforge.net/community/cca08 _______________________________________________ open-axiom-devel mailing list open-axiom-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/open-axiom-devel
