On Sat, Sep 5, 2009 at 6:49 AM, Maurizio<[email protected]> wrote:
>
> Why don't we close this ticket?
>
> http://trac.sagemath.org/sage_trac/ticket/4566
>
> There seems to be already a quite reasonable explanation to do this in
> its comments
I just tried the problem listed there:
sage: timeit("maxima.eval('assume(x>0)')")
5 loops, best of 3: 1.29 ms per loop
sage:
sage: timeit("assume(x>0)")
5 loops, best of 3: 40.2 µs per loop
So it's definitely solved! I closed the ticket.
>
> Maurizio
>
> On 4 Set, 15:34, Burcin Erocal <[email protected]> wrote:
>> Hi Jason and anybody interested in symbolics in Sage,
>>
>> On Fri, 04 Sep 2009 07:33:12 -0500
>>
>>
>>
>> Jason Grout <[email protected]> wrote:
>>
>> > Golam Mortuza Hossain wrote:
>>
>> > > On Sep 3, 10:52 am, Nicolas <[email protected]> wrote:
>> > >> I am trying to do the following thing but I am not sure whether
>> > >> this is possible in sage (though I think it is in Mathematica)
>>
>> > >> Let's say I define a symbolic function
>>
>> > >> sage: f=function('f',x)
>>
>> > >> I would like to issue some command to "tell" sage what the
>> > >> derivative of f is (for instance : g) so that the command
>>
>> > >> sage: diff(f)
>>
>> > >> would yield g
>>
>> > > Yes, its possible also in Sage. I am giving you an example that you
>> > > can adapt for your need. (if you have have a function of multiple
>> > > arguments then you should read diff_param keywords. For example,
>> > > try heaviside?? in sage prompt to see how to read diff_param)
>>
>> > > --------
>> > > sage: g = function('g')
>> > > sage: def f_deriv(*args, **kwds):
>> > > ....: return g(*args)
>> > > ....:
>> > > sage: f = function('f', derivative_func=f_deriv)
>>
>> > Where is this documented? I see some examples (of this and lots of
>> > other keywords) under:
>>
>> > sage.symbolic.function.SFunction??
>>
>> > But I don't think most users would use sage_search or grep to find it
>> > like I had to resort to after guessing a bunch of places the
>> > documentation might be...
>>
>> > It looks like there are quite a lot of very interesting and useful
>> > arguments to function. I had no idea these existed!
>>
>> This is some of the new functionality that came with the GiNaC wrapper.
>> It was one of the first things I wrapped, and in the rush for the
>> switch over from maxima, it still remains in its raw state.
>>
>> The interface to define new functions needs more care and polish. ATM,
>> you define a class with methods _eval_, _evalf_, _derivative_, etc. and
>> your function ends up being an instance of this class. I find this
>> rather confusing and would appreciate any suggestions on other design
>> options.
>>
>> There are still lots of rough edges in the new symbolics code. I don't
>> have time to fix all these problems or write documentation. Though, I
>> will do my best to answer questions and explain any tricky parts of the
>> new symbolics to anybody interested, and put in the work to make the
>> required changes (if any) at the c++ level in pynac.
>>
>> So if you're interested in getting the symbolics up to snuff, please
>> take the plunge and look at the new symbolics code in sage/symbolic/.
>>
>> There are lot's of symbolics bugs on trac:
>>
>> http://is.gd/2SqFy[symbolics]http://is.gd/2SqMs[calculus]
>>
>> I can help fix the ones related to new symbolics, #6220 looks like a
>> good start for example.
>>
>> If there is interest we can even hold a symbolics bug day where we meet
>> on IRC and work on some of these.
>>
>> Cheers,
>> Burcin
>>
>> P.S. Many thanks to Karl-Dieter and Golam for the patches waiting for
>> review on trac. I'll try to do the reviews this weekend if no one gets
>> there first.
> >
>
--
William Stein
Associate Professor of Mathematics
University of Washington
http://wstein.org
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