Tolerance is an ugly thing, I guess. http://code.jsoftware.com/wiki/Essays/Tolerant_Comparison
Thanks, -- Raul On Wed, Sep 13, 2017 at 11:23 AM, Erling Hellenäs <[email protected]> wrote: > Floor and ceiling and eq in j all uses comparison tolerance, So when the > result is set to 0 if floor and ceiling are equal in the J sense, we get the > zero result. The question s then if this is the correct behaviour. > > As we can see floor uses comparison tolerance. It is not obvious to me why. > It is not a comparison. If it didn't, we would get the correct result. > > Another possibility is to use comparison tolerance = 0 for floor and ceiling > only here, if that would be what we consider correct behaviour. > > q=: 5729082486784839 % 196 > > 30j5":q > 29230012687677.75000 > 30j5":<.q > 29230012687678.00000 > 30j5":>.q > 29230012687678.00000 > 30j5":(>.q) = <.q > 1.00000 > > > 9!:19]0 > > > 30j5":q > > 29230012687677.75000 > > 30j5":<.q > > 29230012687677.00000 > > 30j5":>.q > > 29230012687678.00000 > > 30j5":(>.q) = <.q > > 0.00000 > > > Cheers, > > > Erling > > > > Den 2017-09-13 kl. 16:34, skrev Raul Miller: >> >> Hmm... actually... no... >> >> The relevant implementation here is in ve.c: >> >> static D jtremdd(J jt,D a,D b){D q,x,y; >> if(!a)R b; >> ASSERT(!INF(b),EVNAN); >> if(a==inf )R 0<=b?b:a; >> if(a==infm)R 0>=b?b:a; >> q=b/a; x=tfloor(q); y=tceil(q); R teq(x,y)?0:b-a*x; >> } >> >> No hint of fmod here (though it does get used elsewhere). >> >> FYI, >> > > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
