On Sat, 17 May 2025 11:25:58 GMT, fabioromano1 <d...@openjdk.org> wrote:
>> The [Rampdown Phase One](https://openjdk.org/projects/jdk/25/) for JDK 25 is >> about 3 weeks from now. >> >> I think it's a bit too late for API additions to be approved in due time. >> And even if we could rush this work for 25, it makes little sense to have >> this in 25 and the future one in 26. IMO, they should be released together. >> So this and the followup PR for `BigDecimal` will probably be integrated >> only in 26. >> >> In other words, take your time ;-) > > @rgiulietti Regarding the tests for _n_-th root, the tests for `sqrt()` could > be extended in order to test also `nthRoot()`. @fabioromano1 IIUC, the bulk of the code in the PR is aimed at finding a good starting estimate. Algorithm 1.14 RootInt in [Brent & Zimmermann](https://maths-people.anu.edu.au/~brent/pd/mca-cup-0.5.9.pdf), p. 27-28, however, works for any initial estimate $u$ meeting $u \ge \lfloor m^{1/k}\rfloor$. Now, assume $2^{l-1} \le m < 2^l$. We have $m^{1/k} < 2^{l/k} \le 2^{\lceil l/k\rceil}$ Thus, the initial estimate could be simple as $u = 2^{\lceil l/k\rceil}$. This has the following advantages: * It's super-easy to determine. * Computing the _first_ $t = (k - 1) s + \lfloor m/s^{k-1}\rfloor$ (L.4 of RootInt) is quite efficient and can be done separately using shifts and additions. I don't know if this has some negative impact on performance in practice, but IMO the resulting code is easier to review, understand, and maintain. Maybe worth giving it a try. WDYT? ------------- PR Comment: https://git.openjdk.org/jdk/pull/24898#issuecomment-3057905134
