Re: [Maxima-discuss] Small practical problem

[Gunter K. <gu...@pe...>]

Hey! Thanks!

I never expected to happen to end up this near to the name of the thing
I actually needed.

Thanks a lot!

and Kind regards,

 Gunter.

On 07.07.2016 22:27, Robert Dodier wrote:
> On 2016-07-07, Gunter Königsmann <gu...@pe...> wrote:
> 
>> is_y(x):=if x=y then y else 0;
> 
>> sum(
>>     is_y(x),
>>     x,0,inf
>> );
> 
> Well, you can write is_y as is_y(x) := y*kron_delta(x,y); and then apply
> the kron_delta summation stuff I wrote a while ago. Here's what I get:
> 
>   (%i1) load ("sum_kron_delta.mac");
>   (%o1)                         sum_kron_delta.mac
>   (%i2) is_y(x) := y * kron_delta(x, y) $
>   (%i3) sum (is_y(x), x, 0, inf);
>   (%o3)      (if (0 <= y) and %elementp(y, integers) then 1 else 0) y
> 
> With assumptions on y namely assume(y > 0) and declare(y, integer) the
> result simplifies to y.
> 
> Here's a link to the current version of sum_kron_delta.mac:
> https://pastebin.com/gm3uggMe
> 
> Hope this helps,
> 
> Robert Dodier
> 
> 
> ------------------------------------------------------------------------------
> Attend Shape: An AT&T Tech Expo July 15-16. Meet us at AT&T Park in San
> Francisco, CA to explore cutting-edge tech and listen to tech luminaries
> present their vision of the future. This family event has something for
> everyone, including kids. Get more information and register today.
> http://sdm.link/attshape
> _______________________________________________
> Maxima-discuss mailing list
> Max...@li...
> https://lists.sourceforge.net/lists/listinfo/maxima-discuss
>