#15071: Make it easy to have automatic numerical evaluation of symbolic
functions
on inexact input
-------------------------------+-------------------------------
Reporter: eviatarbach | Owner:
Type: enhancement | Status: positive_review
Priority: major | Milestone: sage-5.12
Component: symbolics | Resolution:
Keywords: | Merged in:
Authors: | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
Dependencies: | Stopgaps:
-------------------------------+-------------------------------
Changes (by benjaminfjones):
* status: needs_review => positive_review
Old description:
> This ticket is for making it easy to have symbolic functions
> automatically evaluate on inexact input. This is already the behaviour of
> most symbolic functions and as such it would be good to have a standard
> way of implementing it.
>
> This ticket modifies `Function._eval_default` to accept an arbitrary
> number of arguments. To have the numeric evaluation work, `_eval_default`
> can be assigned to `_eval_`, or it can be called from within `_eval_`
> and, if it returns `None`, leaves opportunity for exact simplification.
> For example,
>
> {{{
> sage: from sage.symbolic.function import BuiltinFunction
> sage: class Test(BuiltinFunction):
> ....: def __init__(self):
> ....: BuiltinFunction.__init__(self, 'test', nargs=1)
> ....: def _evalf_(self, x, parent):
> ....: return 0.5
> ....: def _eval_(self, x):
> ....: y = self._eval_default(x)
> ....: if y:
> ....: return y
> ....: else:
> ....: return 3
> sage: test = Test()
> sage: test(1.3)
> 0.500000000000000
> sage: test(pi)
> 3
> }}}
New description:
This ticket is for making it easy to have symbolic functions automatically
evaluate on inexact input. This is already the behaviour of most symbolic
functions and as such it would be good to have a standard way of
implementing it.
This ticket modifies `Function._eval_default` to accept an arbitrary
number of arguments. To have the numeric evaluation work, `_eval_default`
can be assigned to `_eval_`, or it can be called from within `_eval_` and,
if it returns `None`, leaves opportunity for exact simplification. For
example,
{{{
sage: from sage.symbolic.function import BuiltinFunction
sage: class Test(BuiltinFunction):
....: def __init__(self):
....: BuiltinFunction.__init__(self, 'test', nargs=1)
....: def _evalf_(self, x, parent):
....: return 0.5
....: def _eval_(self, x):
....: y = self._eval_default(x)
....: if y:
....: return y
....: else:
....: return 3
sage: test = Test()
sage: test(1.3)
0.500000000000000
sage: test(pi)
3
}}}
----
Apply trac15071_4.patch
--
Comment:
All tests pass! Positive review.
--
Ticket URL: <http://trac.sagemath.org/ticket/15071#comment:13>
Sage <http://www.sagemath.org>
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