On Fri, Feb 5, 2010 at 9:10 AM, John Cremona <john.crem...@gmail.com> wrote: > On 5 February 2010 16:18, William Stein <wst...@gmail.com> wrote: >> On Fri, Feb 5, 2010 at 8:12 AM, John Cremona <john.crem...@gmail.com> wrote: >>> Here's the explanation. I had thought that check=False just stops the >>> check that the equations are satisfied (I posted an examples where >>> there were no equations which perhaps hid my point; I found this >>> while constructing points on a curve in P^2). But in fact it checks >>> nothing at all. >>> >>> All I would want to do is change the line self._coords = v to >>> self._coords = list(v) at the appropriate place. If that failed, then >>> it's the user's false. In this case it did not fail and almost >>> everything worked, except that I got inconsistencies in sorting points >>> since the sort function tearted a point with _coords as list >>> differently from points with _coords as tuple! >> >> But the reason for check=False is that it is useful for writing >> internal code, where you want >> to avoid the potentially substantial overhead of operations such as >> "list(v)". > > I did not know that was potentially expensive. If so, let the code be > as it is -- but then whenever a function has a "check-False" option > the exact correct input should be documented. Which it is NOT at
Yes, I strongly agree with this. Please open a trac ticket. We can even include your example that stung you. > present: > > sage: F = GF(2^6,'a') > sage: P2.<X,Y,Z> = ProjectiveSpace(F,2) > sage: C = Curve(X^5+11*X*Y*Z^3 + X^2*Y^3 - 13*Y^2*Z^3) > sage: C.point? > Type: instancemethod > Base Class: <type 'instancemethod'> > String Form: <bound method ProjectiveCurve_finite_field.point of > Projective Curve over Finite Field in a of size 2^6 defined by X^5 + > X^2*Y^3 + X*Y*Z^3 + Y^2*Z^3> > Namespace: Interactive > File: > /home/jec/sage-4.3.2.rc0/local/lib/python2.6/site-packages/sage/schemes/generic/scheme.py > Definition: C.point(self, v, check=True) > Docstring: > x.__init__(...) initializes x; see x.__class__.__doc__ for signature > > I made assumptions about using check=False, and was wrong, and got stung! > > John > >> >> Maybe we need another option? E.g., check_ring or something? >> >> -- William >> >> -- >> To post to this group, send an email to sage-devel@googlegroups.com >> To unsubscribe from this group, send an email to >> sage-devel+unsubscr...@googlegroups.com >> For more options, visit this group at >> http://groups.google.com/group/sage-devel >> URL: http://www.sagemath.org >> > > -- > To post to this group, send an email to sage-devel@googlegroups.com > To unsubscribe from this group, send an email to > sage-devel+unsubscr...@googlegroups.com > For more options, visit this group at > http://groups.google.com/group/sage-devel > URL: http://www.sagemath.org > -- William Stein Associate Professor of Mathematics University of Washington http://wstein.org -- To post to this group, send an email to sage-devel@googlegroups.com To unsubscribe from this group, send an email to sage-devel+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-devel URL: http://www.sagemath.org
