On Friday, March 21, 2014 9:51:22 AM UTC-7, Aaron Meurer wrote: > > Well, that particular example falls out of the scope of the assumption > system (it happens directly in the core). > > I was looking for something more like sin(non-zero rational) == > irrational, but sin(float) evaluates to float. >
If you want to prove things about the mathematical function sin, don't expect to do it with the numerical function. In FORTRAN they used to be called sinf(<single_float>) and sind(<double_float>) but programming languages today are so clever that they put them both, and some other things all under the name sin(). This doesn't mean they are REALLY the same, and that's one of the costs of having a programming language and a mindset that is billed as "easy to learn". RJF > > Aaron Meurer > > On Thu, Mar 20, 2014 at 4:57 PM, Sergey B Kirpichev > <[email protected] <javascript:>> wrote: > > On Thu, Mar 20, 2014 at 04:35:43PM -0500, Aaron Meurer wrote: > >> Can you think of a fact in the assumptions system (implemented or not) > >> that would break if floats are rational? > > > > Any, that uses algebraic properties of the rational numbers field. > > > > An example, associativity: > > "((x + y) + z) - (x + (y + z)) is zero" > > > > -- > > 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/20140320215724.GA7879%40darkstar.order.hcn-strela.ru. > > > > 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/97f6e4b8-205e-4652-9b38-2c16dc91d412%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
