I guess APL standard is really bad in this regard. Dyalog APL gives the following:
Dyalog APL/S-64 Version 15.0.27700 Unicode Edition Tue Jun 20 10:46:08 2017 5J3|14J5 1J4 5J3|1J4 ¯4J1 5J3|¯4J1 ¯4J1 which coincides with the previous gnu apl result. > On Jun 20, 2017, at 3:02 AM, Jay Foad <jay.f...@gmail.com> wrote: > > With the demo version of APL2 I get: > > 5J3 ∣ 14J5 > ¯4J1 > 5J3 | 1J4 > ¯4J1 > 5J3 | ¯4J1 > ¯4J1 > > Jay. > > On 19 June 2017 at 18:03, Frederick Pitts <fred.pit...@comcast.net> wrote: > Jürgen, > > With gnu apl (svn 961 on Fedora 25, Intel(R) Core(TM) i7-6700 > CPU), the residue function (∣) yields the following: > > 5J3 ∣ 14J5 > 1J4 > 5J3 | 1J4 > ¯4J1 > 5J3 | ¯4J1 > ¯4J1 > The above result means that two elements in the complete residue system > (CSR) for mod 5J3 are equal, i.e. 1J4 = ¯4J1 mod 5J3, which is not > allowed. None of the elements of a CSR can be equal modulo the CSR's > basis. > > Regards, > > Fred > >