On Tue, 22 Nov 2011 09:41:56 -0800 (PST) kcrisman <kcris...@gmail.com> wrote:
> > > > I don't think it exists, The symbolic functionality in Sage is > > > supposed to make it "easy" for users to define a new symbolic > > > function at runtime, including how that function gets simplified. > > > This is supposed to not involve any C++ coding with Pynac. So > > > it _should_ be easy to add what you suggest. Maybe Burcin can > > > pipe up. > > > > Here is a symbolic function which wraps RR.nth_root(): > > > > from sage.symbolic.function import BuiltinFunction, is_inexact > > from sage.symbolic.expression import Expression > > from sage.structure.coerce import parent > > > > class RealNthRoot(BuiltinFunction): > > def __init__(self): > > BuiltinFunction.__init__(self, "real_nth_root", nargs=2) > > > > def _eval_(self, base, exp): > > if (not isinstance(base, Expression) and is_inexact(base)) > > or \ (not isinstance(exp, Expression) and is_inexact(exp)): > > self._evalf_(base, exp, parent=parent(base)) > > > > def _evalf_(self, base, exp, parent=None): > > if isinstance(base, float): > > return RR(base).nth_root(exp) > > try: > > return base.nth_root(exp) > > except AttributeError: > > return base**(1/exp) > > return parent(base)**parent(exp) > > > > The code is also here: > > > > http://sage.math.washington.edu/home/burcin/real_nth_root.py > > > > I can plot this without trouble: > > > > sage: attach real_nth_root.py > > sage: real_nth_root = RealNthRoot() > > sage: v = real_nth_root(x, 3) > > sage: plot(v, (x, -1, 1)) > > <firefox displays the plot> > > Maybe this would be the best solution. If you put this on a ticket > with patch I'll try to make sure this gets reviewed properly at Sage > Days 35.5. Thanks! I attached a patch to #12074. Still needs documentation and tests. http://trac.sagemath.org/sage_trac/ticket/12074 Cheers, Burcin -- 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
