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Talk:Sum of divisors

From Rosetta Code

already here as "Proper divisors" ?[edit]

...   (Replying to non-existent text that wasn't included here when this talk section was created   ---   first time I ever saw a talk section created without any content (text) in it,   it's rather awkward to discuss a topic without any content, per se)         I also changed the talk section name by adding a question mark.


So,   I don't believe that the above mentioned task   Proper divisors   is already here as a task by another name.

The Rosetta Code task   Proper divisors   required:

  •   write a routine to find (generate) all the proper divisors of an integer,
  •   display a list of the proper divisors for a list of numbers,   and
  •   find a number  (up to some limit)  that has the most proper divisors.


This Rosetta Code task is to   sum   the divisors     (divisors,   not   proper divisors).

There is (or can be) some overlap as there are minor differences between   divisors   and   proper divisors,   the case for unity being one of them.     This task  (Sum of divisors)   is different enough to warrant it's own Rosetta Code task.   -- Gerard Schildberger (talk) 16:48, 20 December 2020 (UTC)

I saw that page but really, this one includes n itself, it is the one the most needed and there are many formulas to do it. --Blek
Perhaps that phrase the one the most needed expresses a slight misunderstanding about the nature and goals of Rosetta Code ?
You will see, on the landing page, that Rosetta aims for contrastive insight – not for comprehensive coverage of homework questions :-) The scope for contrastive insight in the matter of divisors is already exhausted by the trivially different Proper divisors task. Hout (talk) 17:50, 20 December 2020 (UTC)

I think this task should be the main task.

Check the literature to see how this task has inspired scientists.

I think like factorial where we can find many tasks in Rosetta given the insight of factorial, we still have factorial because it is a must. I think this task is like factorial. We shouldn't miss it.

Depends on the algorithm you use...[edit]

I think what Blek is trying to say is that finding the sum of the proper divisors of a number isn't necessarily the same as finding the divisors and adding them up. There are other algorithms other than the "obvious" one. --Tigerofdarkness (talk) 19:29, 21 December 2020 (UTC)

+1 for this. Perhaps the task should ask for more than the first 100 which is trivial, provides no insight, and can be done with any algorithm. Perhaps asking for the largest sum of divisors in the first 3 million positive integers would discourage trivial factorization algorithms.--Nigel Galloway (talk) 15:07, 9 March 2021 (UTC)

how do I sign my name ?[edit]

PS: Please, how to print my user name and the time when I write here? --Blek

You put --~~~~ --Tigerofdarkness (talk) 18:35, 20 December 2020 (UTC)
Thanks --Blek (talk)
What you can do is append to the end of your text,   you can add:     -- ~~~~
the two minus signs followed by four tildes separate your name and timestamp from the preceding text.     -- Gerard Schildberger (talk) 18:50, 20 December 2020 (UTC)
Don't forget to indent your replies with some number of leading colons,   one more than the previous post.     -- Gerard Schildberger (talk) 18:50, 20 December 2020 (UTC)
I succeeded. Thanks! --Blek (talk) 21:30, 20 December 2020 (UTC)
The other day someone asked me, so I went looking for a link for this, rather than try and explain it myself, and was fairly surprised there doesn't seem to be one, so it seems like every new joiner has to ask just like this... --Pete Lomax (talk) 04:57, 22 December 2020 (UTC)