On Tue, 8 Dec 2009 21:57:30 -0800
Robert Bradshaw <rober...@math.washington.edu> wrote:
<snip>
> > On Wed, Dec 9, 2009 at 12:44 PM, Nick Alexander
> > <ncalexan...@gmail.com> wrote:
<snip>
> >> You need to subclass sage.symbolic.function.SFunction. I don't see
> >> many examples, so here is a minimal one:
> >>
> >> from sage.symbolic.function import SFunction
> >> from sage.rings.all import RealField
> >>
> >> class bessel_J_class(SFunction):
> >> def __init__(self, *args, **kwds):
> >> kwds['nargs'] = 2
> >> kwds['evalf_func'] = self._evalf_func_
> >> SFunction.__init__(self, "bessel_J", *args, **kwds)
> >>
> >> def _evalf_func_(self, *args, **kwds):
> >> prec = kwds['prec']
> >> vals = [ arg.n(prec) for arg in args ]
> >> v = bessel_J(*vals)
> >> return RealField(prec)(v)
> >>
> >> symbolic_bessel_J = bessel_J_class()
> >>
> >> Then the following works for me:
> >>
> >> sage: var('x')
> >> sage: plot(symbolic_bessel_J(0, x), (x, 0, 100))
This is also #1158 on trac:
http://trac.sagemath.org/sage_trac/ticket/1158
<snip>
> Any thoughts on making a symbolic decorator, so one could do
> something like
>
> @sage.symbolic.function.symbolic
> def my_func(x, n):
> if x < 0: return 0
> else: return exp(-1/x^n)
>
> ?
Great idea! I opened a ticket:
http://trac.sagemath.org/sage_trac/ticket/7636
I'll implement this first chance I get.
Cheers,
Burcin
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