On Thu, Mar 10, 2016 at 08:17:43AM +0100, Jeroen Demeyer wrote: > On 2016-03-09 23:56, Thierry wrote: > >Willing to > >change the behaviour will be similar to requesting that 'NaN in RR' should > >return False. > Not the topic of this thread, but I really think that "NaN in RR" should > return False. RR represents the real numbers and NaN is *not a number*.
RR does *not* correspond to the real numbers, at least not in the way that NN, ZZ, QQ, AA, QQbar do. RR is just a MPFR representation of numbers, among various other representations, such as RDF, RIF, RBF,... The particular RR name is ill-chosen, but RR is nothing but a slower implementation of RDF, whose second letter clearly insist on the representation (an information that is missing for RR). The benefit of MPFR over CPU-floats is when we use more than 53 bits of precision. The focus on MPFR among other representations is imho a mistake. See http://trac.sagemath.org/ticket/17713#comment:3 > Note that Sage usually defines "x in P" as "P(x) == x" which would > actually give False for NaN since NaN != NaN. The NaN in the namespace is from SR, so the equality RR(NaN)==NaN is coerced in SR, in which NaN equals NaN. Ciao, Thierry > Whether Infinity should be in RR is a more borderline question, but I don't > mind that RR(1)/RR(0) gives Infinity. > > -- > You received this message because you are subscribed to the Google Groups > "sage-devel" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > Visit this group at https://groups.google.com/group/sage-devel. > For more options, visit https://groups.google.com/d/optout. -- You received this message because you are subscribed to the Google Groups "sage-devel" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.
