@Sean Owen <sro...@gmail.com> Thank you very much. And I saw your reply comment in https://issues.apache.org/jira/browse/SPARK-28519, I will test with modification and to see whether there are other similar tests fail, and will address them together in one pull request.
On Sat, Jul 27, 2019 at 9:04 PM Sean Owen <sro...@gmail.com> wrote: > Great thanks - we can take this to JIRAs now. > I think it's worth changing the implementation of atanh if the test value > just reflects what Spark does, and there's evidence is a little bit > inaccurate. > There's an equivalent formula which seems to have better accuracy. > > On Fri, Jul 26, 2019 at 10:02 PM Takeshi Yamamuro <linguin....@gmail.com> > wrote: > >> Hi, all, >> >> FYI: >> >> @Yuming Wang the results in float8.sql are from PostgreSQL directly? >> >> Interesting if it also returns the same less accurate result, which >> >> might suggest it's more to do with underlying OS math libraries. You >> >> noted that these tests sometimes gave platform-dependent differences >> >> in the last digit, so wondering if the test value directly reflects >> >> PostgreSQL or just what we happen to return now. >> >> The results in float8.sql.out were recomputed in Spark/JVM. >> The expected output of the PostgreSQL test is here: >> https://github.com/postgres/postgres/blob/master/src/test/regress/expected/float8.out#L493 >> >> As you can see in the file (float8.out), the results other than atanh >> also are different between Spark/JVM and PostgreSQL. >> For example, the answers of acosh are: >> -- PostgreSQL >> >> https://github.com/postgres/postgres/blob/master/src/test/regress/expected/float8.out#L487 >> 1.31695789692482 >> >> -- Spark/JVM >> >> https://github.com/apache/spark/blob/master/sql/core/src/test/resources/sql-tests/results/pgSQL/float8.sql.out#L523 >> 1.3169578969248166 >> >> btw, the PostgreSQL implementation for atanh just calls atanh in math.h: >> >> https://github.com/postgres/postgres/blob/master/src/backend/utils/adt/float.c#L2606 >> >> Bests, >> Takeshi >> >>
