20221020, 15:30  #45 
Bamboozled!
"๐บ๐๐ท๐ท๐ญ"
May 2003
Down not across
5×17×137 Posts 
Undoubtedly the case. It can run in O(log(N)) number of GCDs, where N is the number of primes, whereas it takes O(N) by successive trial division. A GCD is also sublinear in the number of basic arithmetic operations.

20221020, 16:06  #46 
"Oliver"
Sep 2017
Porta Westfalica, DE
1,319 Posts 
So it sounds like it would be a workable idea to back FactorDB up by simply downloading all the primes. Maybe we can ask Markus whether he is up to giving some of us a download link for these?

20221020, 19:29  #47  
If I May
"Chris Halsall"
Sep 2002
Barbados
2^{2}·5·7·79 Posts 
Quote:
Just to put this out there... I often use rsync for IPC data exchange. Whenever possible, stand on the shoulders of giants. 

20221021, 00:05  #48  
"Alexander"
Nov 2008
The Alamo City
2×3^{3}×17 Posts 
Quote:
Last fiddled with by Happy5214 on 20221021 at 00:06 Reason: Clip 

20221023, 01:01  #49 
"Alexander"
Nov 2008
The Alamo City
2·3^{3}·17 Posts 
I'd like to add that, for a database website, its understanding of HTTP methods is terrible. GET requests should not change meaningful data, including creating new entries, especially without explicitly declaring that intent. That's just a basic rule of web design. Ideally, all new IDs would be created through POST or PUT requests, and queries that result in a nonexistent entry would return the queried formula or say "entry not found" (or something similar).
Last fiddled with by Happy5214 on 20221023 at 01:02 Reason: Clarify 
20221029, 08:21  #50  
Romulan Interpreter
"name field"
Jun 2011
Thailand
24041_{8} Posts 
Quote:
Once you start "solving" the aliquot 100, this will add to the database the line for 100, and the line for 117, etc. When the sequence 100 is finished (it may or may not be in this step  think about numbers with many digits, not about 117 itself which is very easy to factor  finishing the sequence starting with 100 may take years )  and we will find out that 100 ends in 19 too, then the line for 19 will look like "19, 1, 65 100" (as 100 is longer than 65). You don't need to "finish" the sequence 100, as immediately when you will get to 65, you will find that in the DB already, looking like "65, 5, 13, 65, 65" (see note below about flags and cofactor) and this will be modified to "65, 5, 13, 65, 100" (or "65, 5, 100 F", see below). Job done. Also, 77 is never "lost", it has its own line in the DB, that looks like "77, 7, 11, 77, 77" (note that 11 can be missing, and I ignored flags, to avoid complicating the explanation  in fact, the line for 77 is, assuming you only got to 100, "77, 7, F"  the flags can signal there is no merge here, yet, and that it is fully factored, so you don't need to store the last cofactor and the double 77 at the end  this is not the same F as above, it is used generic  about 7 bits will be enough to keep al situations, so the flag will always be a small decimal number). So, what's your problem? Last fiddled with by LaurV on 20221029 at 08:44 

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