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4:23 AM
@CATrevillian, put a Print statement in and see what order they are done in. ParallelTable[Print[{i, j}]; Pause[i*j/20], {i, 1, 10}, {j, 1, 10}] seems to send $i=1$ and $i=4$ to the subkernels first for me, slightly strangely. Don't know the answer to the other parts.
 
 
2 hours later…
6:50 AM
Thanks @KraZug! That’s a great idea. Seems to me, then, that Table tosses back whole lists at a time per the outer most index (the inner most defined one in Table).
 
 
4 hours later…
10:54 AM
I sometimes wonder whether there is a way to have a canonical "how do I rewrite an expression in terms of other expressions" Q&A - it seems questions on this pop up every other week... (e.g here)
Thoughts?
 
 
3 hours later…
1:56 PM
@CATrevillian, yes, I agree that is what it looks like it does. Don't know why it doesn't send $i=1$ and $i=2$ to the subkernels and instead chooses 1 and 4.
 
2:35 PM
@CATrevillian Trace might give you some additional insight? e.g. Table[i*j/20, {i, 1, 10}, {j, 1, 10}] // Trace
 
2:54 PM
@KraZug for whatever reason, that isn't too concerning or confusing or unexpected to me, but I can't explain why exactly...how many cores would you be running?
@kirkus ah nice! I forget about trace, wow, ok--some interesting outputs came out, some REALLY interesting outputs WOW...I honestly don't know what to make of it, with ParallelTable it is...very internal looking, low-level as could be! It should be super interesting to study this :D lots of iconized outputs hidden in there too. This is exciting
 
3:18 PM
While cleaning my garage I found something that might alleviate my need for Mathematica...
5
 
3:37 PM
@KraZug it looks like it judiciously separates them into equal parts, or as equal as it can, for each kernel. See here:
`ParallelTable[{i, j, $KernelID}, {i, 1, 12}, {j, 1, 12}]`
(*{{{1, 1, 6}, {1, 2, 6}, {1, 3, 6}, {1, 4, 6}, {1, 5, 6}, {1, 6,
6}, {1, 7, 6}, {1, 8, 6}, {1, 9, 6}, {1, 10, 6}, {1, 11, 6}, {1,
12, 6}}, {{2, 1, 6}, {2, 2, 6}, {2, 3, 6}, {2, 4, 6}, {2, 5,
6}, {2, 6, 6}, {2, 7, 6}, {2, 8, 6}, {2, 9, 6}, {2, 10, 6}, {2, 11,
6}, {2, 12, 6}}, {{3, 1, 5}, {3, 2, 5}, {3, 3, 5}, {3, 4, 5}, {3,
5, 5}, {3, 6, 5}, {3, 7, 5}, {3, 8, 5}, {3, 9, 5}, {3, 10, 5}, {3,
11, 5}, {3, 12, 5}}, {{4, 1, 5}, {4, 2, 5}, {4, 3, 5}, {4, 4,
5}, {4, 5, 5}, {4, 6, 5}, {4, 7, 5}, {4, 8, 5}, {4, 9, 5}, {4, 10,
 
 
1 hour later…
5:20 PM
posted on September 19, 2019

Science & Technology

 
5:52 PM
I am working on a heuristic algorithm that tries to find a representation in radicals for polynomial roots of degree >4, in part based on mathematica.stackexchange.com/a/134551/7288, mathematica.stackexchange.com/q/34011/7288 and mathematica.stackexchange.com/q/105933/7288.
It appears that many roots "naturally occurring" in analysis are solvable in radicals. E.g., see results in math.stackexchange.com/a/3345906/19661, math.stackexchange.com/a/3353410/19661 and math.stackexchange.com/a/3353303/19661. Can anybody please provide more polynomials of higher degrees that might be solvable in radicals, which I could use to validate and improve my algorithm?
 
 
2 hours later…
8:04 PM
@CATrevillian, @KraZug The actual code doing the dispatch seems to be in Parallel`Combine`Private`parallelIterateE, with the batch sizes being determined in Parallel`Combine`Private`grokMethodOption - the Automatic size is in fact Ceiling[(iterations/$KernelCount)^(2/3)] by the looks of it
 
9:01 PM
posted on September 19, 2019

Science & Technology

 

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