On Mon, Apr 5, 2010 at 9:12 PM, Michael Welsh <[email protected]> wrote: > > On 6/04/2010, at 3:56 PM, Eugene Goldberg wrote: > >> Hello! >> >> Here is my pyhtons results: >> >> python >> Python 2.6.5 (r265:79063, Mar 23 2010, 04:49:54) >> [GCC 4.4.3] on linux2 >> Type "help", "copyright", "credits" or "license" for more information. >>>>> 1+1 >> 2 >>>>> 6e-6 % 10e-6 >> 6.0000000000000002e-06 >>>>> >> >> and here is sage: >> >> ./ >> sage >> Sage Version 4.3.5, Release Date: >> 2010-03-28 >> sage: 1+1 >> 2 >> sage: 6e-6 % 10e-6 >> -4.00000000000000e-6 >> >> I'm sure sage is wrong.. :( > > They're both the same...
No they aren't. If you type sage: s = 6e-6 sage: s.__mod__?? then you can read the documentation for Sage's % on real numbers. Definitely the result sage: 6e-6 - 10e-6 -4.00000000000000e-6 matches what is claimed in the docstring. The actual function calls the MPFR function "mpfr_remainder", which is documented here: http://www.mpfr.org/algorithms.pdf See Section 3.8. This web page: http://pyref.infogami.com/operator-mod describes the Python semantics for Python's __mod__ on float's. They are different than MPFR's. William -- William Stein Associate Professor of Mathematics University of Washington http://wstein.org -- To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/sage-support URL: http://www.sagemath.org To unsubscribe, reply using "remove me" as the subject.
