{"action":"created","issue":{"url":"https://api.github.com/repos/gap-system/gap/issues/2131","repository_url":"https://api.github.com/repos/gap-system/gap","labels_url":"https://api.github.com/repos/gap-system/gap/issues/2131/labels{/name}","comments_url":"https://api.github.com/repos/gap-system/gap/issues/2131/comments","events_url":"https://api.github.com/repos/gap-system/gap/issues/2131/events","html_url":"https://github.com/gap-system/gap/issues/2131","id":292764374,"number":2131,"title":"Document RootFFE?","user":{"login":"fingolfin","id":241512,"avatar_url":"https://avatars2.githubusercontent.com/u/241512?v=4","gravatar_id":"","url":"https://api.github.com/users/fingolfin","html_url":"https://github.com/fingolfin","followers_url":"https://api.github.com/users/fingolfin/followers","following_url":"https://api.github.com/users/fingolfin/following{/other_user}","gists_url":"https://api.github.com/users/fingolfin/gists{/gist_id}","starred_url":"https://api.github.com/users/fingolfin/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/fingolfin/subscriptions","organizations_url":"https://api.github.com/users/fingolfin/orgs","repos_url":"https://api.github.com/users/fingolfin/repos","events_url":"https://api.github.com/users/fingolfin/events{/privacy}","received_events_url":"https://api.github.com/users/fingolfin/received_events","type":"User","site_admin":false},"labels":[{"id":190798731,"url":"https://api.github.com/repos/gap-system/gap/labels/documentation","name":"documentation","color":"207de5","default":false},{"id":180442299,"url":"https://api.github.com/repos/gap-system/gap/labels/question","name":"question","color":"cc317c","default":true}],"state":"open","locked":false,"assignee":null,"assignees":[],"milestone":{"url":"https://api.github.com/repos/gap-system/gap/milestones/14","html_url":"https://github.com/gap-system/gap/milestone/14","labels_url":"https://api.github.com/repos/gap-system/gap/milestones/14/labels","id":2420535,"number":14,"title":"GAP 4.9.1","description":"First public release of GAP 4.9","creator":{"login":"alex-konovalov","id":5751387,"avatar_url":"https://avatars1.githubusercontent.com/u/5751387?v=4","gravatar_id":"","url":"https://api.github.com/users/alex-konovalov","html_url":"https://github.com/alex-konovalov","followers_url":"https://api.github.com/users/alex-konovalov/followers","following_url":"https://api.github.com/users/alex-konovalov/following{/other_user}","gists_url":"https://api.github.com/users/alex-konovalov/gists{/gist_id}","starred_url":"https://api.github.com/users/alex-konovalov/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/alex-konovalov/subscriptions","organizations_url":"https://api.github.com/users/alex-konovalov/orgs","repos_url":"https://api.github.com/users/alex-konovalov/repos","events_url":"https://api.github.com/users/alex-konovalov/events{/privacy}","received_events_url":"https://api.github.com/users/alex-konovalov/received_events","type":"User","site_admin":false},"open_issues":9,"closed_issues":12,"state":"open","created_at":"2017-03-29T21:59:07Z","updated_at":"2018-03-22T14:56:36Z","due_on":"2018-04-01T07:00:00Z","closed_at":null},"comments":5,"created_at":"2018-01-30T12:26:23Z","updated_at":"2018-03-23T14:29:29Z","closed_at":null,"author_association":"OWNER","body":"@hulpke added a new operation `LowIndexSubgroups` in PR #683, but it is currently undocumented (well, there is a documentation comment, but it is not hooked up into the the reference manual).\r\n\r\nI wonder if this is intentional, or whether perhaps `LowIndexSubgroups` should be documented (and then also on the `stable-4.9` branch)?"},"comment":{"url":"https://api.github.com/repos/gap-system/gap/issues/comments/375683136","html_url":"https://github.com/gap-system/gap/issues/2131#issuecomment-375683136","issue_url":"https://api.github.com/repos/gap-system/gap/issues/2131","id":375683136,"user":{"login":"fingolfin","id":241512,"avatar_url":"https://avatars2.githubusercontent.com/u/241512?v=4","gravatar_id":"","url":"https://api.github.com/users/fingolfin","html_url":"https://github.com/fingolfin","followers_url":"https://api.github.com/users/fingolfin/followers","following_url":"https://api.github.com/users/fingolfin/following{/other_user}","gists_url":"https://api.github.com/users/fingolfin/gists{/gist_id}","starred_url":"https://api.github.com/users/fingolfin/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/fingolfin/subscriptions","organizations_url":"https://api.github.com/users/fingolfin/orgs","repos_url":"https://api.github.com/users/fingolfin/repos","events_url":"https://api.github.com/users/fingolfin/events{/privacy}","received_events_url":"https://api.github.com/users/fingolfin/received_events","type":"User","site_admin":false},"created_at":"2018-03-23T14:29:29Z","updated_at":"2018-03-23T14:29:29Z","author_association":"OWNER","body":"By chance, I just learned that `RootFFE` actually duplicates the functionality of `NthRoot`, for which we install a method in `lib/ffe.gi`, albeit one less efficient (I think) than what `RootFFE` does. \r\n\r\nOf course there is then also an operation `Root` -- but it is \"broken\" in that it only accepts a multiplicative element and (optional) a positive integer n, but not a domain. I guess one could fix that, and install methods for it that mirror `NthRoot` etc. ... hohum. \r\n\r\nOf course `Root` is also undocumented, in particular its semantics are unclear. Since it is declared right next to `Sqrt`, one might expect that `Sqrt(x) = Root(x, 2)`, but this is not the case, as the only method the GAP library installs for `Root` is `RootInt`, which returns the integral part of a root... In particular:\r\n```\r\ngap> Sqrt(5);\r\nE(5)-E(5)^2-E(5)^3+E(5)^4\r\ngap> Root(5,2);\r\n2\r\ngap> Sqrt(-1);\r\nE(4)\r\ngap> Root(-1,2);\r\nError, Root: <n> is negative but <k> is even in\r\n...\r\n```\r\n\r\n*sigh*"}}
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