On Tue, Jun 30, 2009 at 11:52 PM, David Joyner<wdjoy...@gmail.com> wrote:
>
> On Tue, Jun 30, 2009 at 4:26 PM, Fausto Arinos
> Barbuto<fausto.barb...@gmail.com> wrote:
>>
>>
>> Hi all,
>>
>> I'm afraid this question has already appeared in this forum, but here it
>> goes again.
>>
>> I'm curious about why the inverse_laplace() function can't successfully
>> invert some
>> well-known, nevertheless rather simple, functions. Let's take exp(-as)/s as
>> an
>> example, whose inverse is the Heaviside function H(t-a):
>>
>> var('s,t')
>> f = (exp(-s)/s).inverse_laplace(s,t); f
>>
>> The evaluation of the second line produces:
>>
>> ilt(e^(-s)/s, s, t)
>>
>> Which, obviously, is not a satisfactory answer. What happens here?
>>
>> How does inverse_laplace() work?
>
> Right now, inverse_laplace calls maxima and the Heaviside function is not yet
> well-integrated into maxima.
> http://maxima.sourceforge.net/docs/manual/en/maxima_20.html#Item_003a-ilt
> http://maxima.sourceforge.net/docs/manual/en/maxima_19.html#Item_003a-laplace
>
Yes. There is basically nothing to be done by Sage devs until either:
(1) a full new implementation from scratch in Sage / Pynac / whatever
is written of inverse_laplace, which doesn't so directly depend on
Maxima, or
(2) sage devs stop treating Maxima as a black box.
I think (1) is the better longterm solution. A bit of (2) probably
couldn't hurt though.
-- William
--~--~---------~--~----~------------~-------~--~----~
To post to this group, send email to sage-support@googlegroups.com
To unsubscribe from this group, send email to
sage-support-unsubscr...@googlegroups.com
For more options, visit this group at
http://groups.google.com/group/sage-support
URLs: http://www.sagemath.org
-~----------~----~----~----~------~----~------~--~---
