You can prove that any valid IEEE float is a rational (invalid: infinities, NaNs) by looking at the definition.
A fraction (or "mantissa") times an integer power of 2 is always a rational number. Using "*" as a shorthand for "times" does not mean that the intention was to use the defective multiplication in programming languages such as python. Common Lisp has the function rational. (rational 0.1d0) returns 3602879701896397/36028797018963968 which is an integer times 2^(-55). I agree that most hardware and software makes the "inexact" flag difficult to access. Maybe if someone with a popular language made a sufficient fuss, that would change. RJF On Saturday, March 22, 2014 6:00:13 PM UTC-7, Aaron Meurer wrote: > > I'm pretty sure that removing it is the same as setting it to None, > because it falls back to the superclass which sets unknown assumptions > to None. I would set them both explicitly to None to be clear that > that really is what we want, and not just that it isn't implemented. > > Aaron Meurer > > On Sat, Mar 22, 2014 at 1:25 PM, Kalevi Suominen > <[email protected]<javascript:>> > wrote: > > > > > > On Saturday, March 22, 2014 6:24:12 PM UTC+2, Aaron Meurer wrote: > >> > >> Oh, that's good. This was setting is_rational and is_irrational to > >> None? I think that's what they should be. > >> > > I was testing with is_rational commented out (is_irrational does not > exist > > in Float). > > A missing attribute would reveal every attempted use. I think this is > how it > > should > > be in production code, to warn off any accidental use. > > > > Kalevi Suominen > > > > -- > > You received this message because you are subscribed to the Google > Groups > > "sympy" group. > > To unsubscribe from this group and stop receiving emails from it, send > an > > email to [email protected] <javascript:>. > > To post to this group, send email to [email protected]<javascript:>. > > > Visit this group at http://groups.google.com/group/sympy. > > To view this discussion on the web visit > > > https://groups.google.com/d/msgid/sympy/ca368bca-abef-43ec-aba7-7ed55df20d76%40googlegroups.com. > > > > > > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "sympy" 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 http://groups.google.com/group/sympy. To view this discussion on the web visit https://groups.google.com/d/msgid/sympy/8913c2fa-e338-4b0d-a6d3-1fe915d6eb07%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
