On Sunday, February 12, 2017 at 2:11:29 PM UTC-8, John Cremona wrote: > > About 8 years ago I spent a long time making sure that precision was > handled correctly in converting between Sage and pari. Since then the > interface has totally changed and possibly these recent changes are at > fault. > > OK, perhaps it works better than the printing makes us believe:
sage: RealField(200)(2)._pari_().sqrt()._sage_() ^2 2.000000000000000000000000000000000000000000000000000000000000000000000000000 sage: RealField(20)(2)._pari_().sqrt()._sage_() ^2 2.00000000000000000 and indeed, in Pari it seems the default precision doesn't come into play with taking square roots: ? \p 200 realprecision = 211 significant digits (200 digits displayed) ? a=2.0 %8 = 2.0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 ? \p 20 realprecision = 38 significant digits (20 digits displayed) ? sqrt(a)^2-a %9 = -4.752728915737899559 E-212 so I guess the default precision only comes up with more complicated functions such a dilog. -- 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.
