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Extend the range of precomputed simple groups from orders up to 10^18 to orders up to about 10^27 #3861
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In principle this is fine, but the documentation to SimpleGroupsIterator
really should be adjusted to match the code change.
Ideally, a few more changes should be made (see my comment), but that's optional for this PR, and can be done by somebody else (e.g. me) in another PR.
Also: nice patch, thank you :-) |
(based on work of Stefan Kohl) Changed documentation. Fixed also `One/AllSimpleGroup` (why are these there?) and introduced REBASE SIMPLE_GROUPS_ITERATOR_RANGE variable
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Nice! Minor (and optional) remarks added.
pos:=First([1..Length(SIMPLEGPSNONL2)],x->SIMPLEGPSNONL2[x][1]>=start); | ||
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if start>=10^18 then LOADSIMPLE2(); fi; | ||
pos:=First([1..Length(SIMPLEGPSNONL2)],x->SIMPLEGPSNONL2[x][1]>=start); |
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Optional alternative (should be double checked ;-):
pos:=First([1..Length(SIMPLEGPSNONL2)],x->SIMPLEGPSNONL2[x][1]>=start); | |
pos:=PositionProperty(SIMPLEGPSNONL2,x->x[1]>=start); |
Co-Authored-By: Max Horn <[email protected]>
Why 10^27? -- This bound seems a bit arbitrary to me. -- Up to order 10^30, there are 2171 non-PSL2's, up to order 10^40, there are 22709 non-PSL2's, up to order 10^50, there are 298023 non-PSL2's and up to order 10^60, there are 4263813 non-PSL2's. -- Of course listing all the latter in the way you do it now would take hundreds of megabytes of text. -- But that's the reason for the iterator code, instead of using just a list. |
@Stefan-Kohl Yes, 10^27 is arbitary. I don't claim this is the best and end-of-all. If you want to offer your (better) general iterator code as PR, please do so, and I'd be happy to have my code replaced. |
(based on work of Stefan Kohl)
This is -- as basic first option -- simply extending the precomputed list of simple groups of "small" orders from 10^18 to about 10^27
Text for release notes
The range of
SimpleGroupsIterator
has been extended by 9 magnitudes