On Fri, Sep 21, 2012 at 9:38 AM, kcrisman <kcris...@gmail.com> wrote: > > > On Friday, September 21, 2012 11:34:50 AM UTC-4, William wrote: >> >> On Fri, Sep 21, 2012 at 7:53 AM, kcrisman <kcri...@gmail.com> wrote: >> > >> > >> > On Friday, September 21, 2012 9:14:54 AM UTC-4, Peter Mueller wrote: >> >> >> >> In Sage 5.3, the function prime_powers behaves a little strange: >> >> >> >> sage: prime_powers(4,10) >> >> [4, 5, 7, 8, 9] >> >> # As expected >> >> >> >> sage: prime_powers(5,10) >> >> [7, 8, 9] >> >> # 5 isn't a prime power anymore??? >> >> >> >> # And now things become even worse: >> >> sage: prime_powers(7,10) >> >> >> >> >> >> --------------------------------------------------------------------------- >> >> IndexError Traceback (most recent call >> >> last) >> >> >> >> /home/mueller/<ipython console> in <module>() >> >> >> >> >> >> >> >> /home/mueller/local/sage-5.3/local/lib/python2.7/site-packages/sage/rings/arith.pyc >> >> in prime_powers(start, stop) >> >> 743 i = bisect(v, start) >> >> 744 if start > 2: >> >> --> 745 if v[i] == start: >> >> 746 i -= 1 >> >> 747 w = list(v[i:]) >> >> >> >> IndexError: list index out of range >> >> >> > >> > Apparently this hasn't been changed for a long time. "hg blame" leads >> > me to >> > >> > 7046: start, stop = 1, integer.Integer(start) >> > 10906: v = fast_arith.prime_range(stop) >> > 7046: w.insert(0, integer.Integer(1)) >> > >> > where 7046 is http://trac.sagemath.org/sage_trac/ticket/922 which >> > doesn't >> > cover this, and 10906 is from a generic cleanup ticket in 2008. >> > >> > Everything else from this changeset long long ago: >> > >> > 2329103:changeset: 5265:d6107e5bc8b1 >> > 2329134-user: William Stein <wst...@gmail.com> >> > 2329180-date: Mon Jul 02 03:21:30 2007 -0700 >> > 2329224-summary: Add prime_powers function. >> > >> > So I'm amazed that you are the first person to come across this! >> >> A guess why: I (and most people) never used this function except in >> the form prime_powers(B), to compute all prime powers up to B. That's >> probably why this wasn't noticed before. In applications, it is much >> more common to want all prime powers up to a bound, instead of the >> prime powers in an interval. >> >> > > > > Yeah, that's what I had figured for "research uses", but I'm surprised that > no "pedagogical use" case had come up before. > > Does that mean you'll be the one fixing it? ;-)
I'm not going to work on this. William > > -- > You received this message because you are subscribed to the Google Groups > "sage-support" group. > To post to this group, send email to sage-support@googlegroups.com. > To unsubscribe from this group, send email to > sage-support+unsubscr...@googlegroups.com. > Visit this group at http://groups.google.com/group/sage-support?hl=en. > > -- William Stein Professor of Mathematics University of Washington http://wstein.org -- You received this message because you are subscribed to the Google Groups "sage-support" group. To post to this group, send email to sage-support@googlegroups.com. To unsubscribe from this group, send email to sage-support+unsubscr...@googlegroups.com. Visit this group at http://groups.google.com/group/sage-support?hl=en.
