On 5/13/26 12:44 AM, Waldek Hebisch wrote: > On Mon, May 11, 2026 at 11:52:08AM +0800, Qian Yun wrote: >> On 5/11/26 11:49 AM, Waldek Hebisch wrote: >>>> >>>> I guess that Interval did not want to deal with inverse of >>>> [a,b] where a<0<b? >>> >>> Yes, we do not want this: this is moral equivalent of division >>> by 0. >>> >> >> So for the "^" with negative Fraction Integer argument, >> shall we give an error for all intervals, or just for >> intervals that contains 0? > > Negative fractional power should be mostly eqivalent to computing > inverse and then positive power, but should avoid double > rounding impled by composition of operations. Negative > interval can not be raised to power 1/2, and it makes > sense to completely forbid raising negative numbers to > fractional powers (but current version allows this). But > if both lower bound and upper bound are positive, then negative > fractional power is well defined. >
The implementation can be done as such. About Exports: "^ : (%, Integer) -> %" is naturally expressed in DivisionRing. I think it's ok for Interval to have this category. The original authors intention is to stop at Field? - Qian -- You received this message because you are subscribed to the Google Groups "FriCAS - computer algebra system" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion visit https://groups.google.com/d/msgid/fricas-devel/62665956-d5b9-4a91-87a9-4cb179b7fe3c%40gmail.com.
