This bug is tracked now in https://trac.sagemath.org/ticket/34591
On Tuesday, September 27, 2022 at 6:31:39 PM UTC+9 wdjo...@gmail.com wrote: > On Tue, Sep 27, 2022 at 4:46 AM John Cremona <john.c...@gmail.com> wrote: > > > > Am I doing something stupid here, or is this a bug? > > > > sage: R = Integers(8) > > sage: RXY.<X,Y> = R[] > > sage: F = X^3-X^2*Y+X*Y^2+Y^3 > > sage: F([4,2]) > > 6 > > sage: 4^3-4^2*2+4*2^2+2^3 > > 56 > > sage: (4^3-4^2*2+4*2^2+2^3) % 8 > > 0 > > > > Even after coercion it doesn't evaluate in ZZ/8ZZ: > > sage: ZZ8 = IntegerModRing(8) > sage: R.<x,y> = PolynomialRing(ZZ8, "x,y") > sage: f = x^3-x^2*y+x*y^2+y^3 > sage: x0 = ZZ8(4) > sage: y0 = ZZ8(2) > sage: x0^3-x0^2*y0+x0*y0^2+y0^3 > 0 > sage: f(x0,y0) > 6 > sage: f(4,2) > 6 > > > > > Why does F not evaluate to 0 mod 8 at X=4, Y=2? Rather obviously, each > > of the terms in F(4,2) is 0 mod 8. > > > > John > > > > -- > > You received this message because you are subscribed to the Google > Groups "sage-support" group. > > To unsubscribe from this group and stop receiving emails from it, send > an email to sage-support...@googlegroups.com. > > To view this discussion on the web visit > https://groups.google.com/d/msgid/sage-support/CAD0p0K5hXexw5J20gstKUOXxzWdP2a2OTRbKmUtAyG41ySSR-A%40mail.gmail.com > . > -- You received this message because you are subscribed to the Google Groups "sage-support" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-support+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/sage-support/ae69a416-cdb3-4eab-8639-8728152ae3b9n%40googlegroups.com.
