On Mon, 15 Sep 2025 07:39:00 GMT, fabioromano1 <d...@openjdk.org> wrote:
>> A formula to lower the overestimate for the precision of an exact quotient, >> without introducing too expensive operations of division on numerator and >> denominator. > > fabioromano1 has updated the pull request incrementally with one additional > commit since the last revision: > > Optimization HI @fabioromano1, Ah, I haven't worked on that code for exact divide in a while! For some historical context, the method was added as part of JSR 13, Decimal Arithmetic Enhancement, in JDK 5. A fuller derivation of the old bound is discussed in: Fixed, Floating, and Exact Computation with Java's BigDecimalFixed, Floating, and Exact Computation with Java's BigDecimal Dr. Dobb's Journal ยท Jun 1, 2004 https://web.archive.org/web/20210505132021/http://www.drdobbs.com/jvm/fixed-floating-and-exact-computation-wit/184405721 At the time I wrote the code, I looked around at the usual sources, Knuth, etc. and asked around for a bound of decimal digits of 1/b if 1/b is representable, but didn't find anything. I see you're still revising the implementation. Once this settles down, a review comment from me will be "restore some textual discussion of what the algorithm is doing." For testing, I think it would be good to probe at some values where the old and new digit estimation techniques differ. Also, I think both @rgiulietti and myself look at this PR before it goes back; I'll adjust the reviewer count accordingly. ------------- PR Comment: https://git.openjdk.org/jdk/pull/27271#issuecomment-3293076586
