It looks like this discussion just started again on trac, so maybe we should continue the discussion here and/or vote.
To summarize: the consensus on this thread was that automatic coercions should to from RIF to RR, not from RR to RIF. The reason was that elements of RIF represent guaranteed intervals, while elements of RR represent approximations that are expected to have some rounding errors, so if you combine them, then a RIF result will be incorrect. Because of this, trac ticket 15114 was opened, which contains an example of a calculation with an incorrect answer. On that ticket, the user tcoffee mentions two applications that get broken by removing or inverting the coercion RR --> RIF: the use of exact power of 2 from RR and mixing them with RIF to get elements of RIF, and the use of RIF for representing ranges of inexact floating point numbers and mixing those with regular floating point numbers. For details, see the track ticket. So the choices are: 1) explicit conversion RR --> RIF: allow / disallow 2) explicit conversion RIF --> RR: allow / disallow 3) automatic coercisions: disallow / (RR-->RIF) / (RIF-->RR) The current situation afaik (Sage 6.0) is: 1) allow 2) disallow 3) from RR to RIF My vote is: 1) allow 2) allow 3) from RIF to RR Best, Marco Op woensdag 28 augustus 2013 12:00:28 UTC+2 schreef Marco Streng: > > It seems like everyone agrees that coercions from RR to RIF should be > removed, so I created > http://trac.sagemath.org/ticket/15114 > > > > -- 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 sage-devel+unsubscr...@googlegroups.com. To post to this group, send email to sage-devel@googlegroups.com. Visit this group at http://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.
