{"action":"created","issue":{"url":"https://api.github.com/repos/ThreeTen/threeten-extra/issues/43","labels_url":"https://api.github.com/repos/ThreeTen/threeten-extra/issues/43/labels{/name}","comments_url":"https://api.github.com/repos/ThreeTen/threeten-extra/issues/43/comments","events_url":"https://api.github.com/repos/ThreeTen/threeten-extra/issues/43/events","html_url":"https://github.com/ThreeTen/threeten-extra/pull/43","id":83179268,"number":43,"title":"Implemented Symmetry454 chronology","user":{"login":"catull","id":150055,"avatar_url":"https://avatars.githubusercontent.com/u/150055?v=3","gravatar_id":"","url":"https://api.github.com/users/catull","html_url":"https://github.com/catull","followers_url":"https://api.github.com/users/catull/followers","following_url":"https://api.github.com/users/catull/following{/other_user}","gists_url":"https://api.github.com/users/catull/gists{/gist_id}","starred_url":"https://api.github.com/users/catull/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/catull/subscriptions","organizations_url":"https://api.github.com/users/catull/orgs","repos_url":"https://api.github.com/users/catull/repos","events_url":"https://api.github.com/users/catull/events{/privacy}","received_events_url":"https://api.github.com/users/catull/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":2,"created_at":"2015-05-31T20:28:05Z","updated_at":"2015-06-01T14:38:46Z","closed_at":null,"pull_request":{"url":"https://api.github.com/repos/ThreeTen/threeten-extra/pulls/43","html_url":"https://github.com/ThreeTen/threeten-extra/pull/43","diff_url":"https://github.com/ThreeTen/threeten-extra/pull/43.diff","patch_url":"https://github.com/ThreeTen/threeten-extra/pull/43.patch"},"body":"This is an implementation of Symmetry454 as specified under http://individual.utoronto.ca/kalendis/symmetry.htm."},"comment":{"url":"https://api.github.com/repos/ThreeTen/threeten-extra/issues/comments/107533664","html_url":"https://github.com/ThreeTen/threeten-extra/pull/43#issuecomment-107533664","issue_url":"https://api.github.com/repos/ThreeTen/threeten-extra/issues/43","id":107533664,"user":{"login":"catull","id":150055,"avatar_url":"https://avatars.githubusercontent.com/u/150055?v=3","gravatar_id":"","url":"https://api.github.com/users/catull","html_url":"https://github.com/catull","followers_url":"https://api.github.com/users/catull/followers","following_url":"https://api.github.com/users/catull/following{/other_user}","gists_url":"https://api.github.com/users/catull/gists{/gist_id}","starred_url":"https://api.github.com/users/catull/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/catull/subscriptions","organizations_url":"https://api.github.com/users/catull/orgs","repos_url":"https://api.github.com/users/catull/repos","events_url":"https://api.github.com/users/catull/events{/privacy}","received_events_url":"https://api.github.com/users/catull/received_events","type":"User","site_admin":false},"created_at":"2015-06-01T14:38:46Z","updated_at":"2015-06-01T14:38:46Z","body":"I have to mind-read here, not sure where your question is leading.\r\n\r\nAre you asking if the leap-years line up, if the leap year is based on the same formula perhaps ?\r\n\r\nThe Accounting calendar is based on a cycle of 400 years.\r\nIn this cycle, the leap years occur 5, 6 or 7 years apart, giving this delta table:\r\n\r\n6 6 5 6 5 \r\n6 6 5 6 5 \r\n6 6 5 6 5 \r\n6 6 \r\n6 6 5 6 5 \r\n6 6 5 6 5 \r\n6 6 5 6 5 \r\n6 6 5 7 5 6 5 \r\n6 6 5 6 5 \r\n6 6 5 6 5 \r\n6 6 5 \r\n6 6 6 5 \r\n6 6 5 6 5 \r\n6 6 5 6 5 \r\n6 6 5 6 5 \r\n\r\nThe '7' in the middle is no mistake.\r\n\r\nThe Symmetry454 and Symmetry010 (hence unified as SymmetryXYX) have a cycle of 293 years.\r\nThe delta table is:\r\n\r\n6 6 5 6 5 \r\n6 6 5 \r\n6 6 5 \r\n6 6 5 6 5 \r\n6 6 5 \r\n6 6 5 \r\n6 6 5 6 5 \r\n6 6 5 \r\n6 6 5 \r\n6 6 5 6 5 \r\n6 6 5 \r\n6 6 5 \r\n6 6 5 6 5 \r\n6 6 5 \r\n\r\nIf we line up the leap-years of both the Accounting and SymmetryXYX calendars, they are mostly off by 3 and occasionally 2 years.\r\n\r\nStarting from the year 1 of Common Era, these are the first leap years:\r\n\r\nSymmetryXYX:  3,   9, 15, 20, 26, 31, 37, 43, ...\r\nAccounting     :  6, 12, 17, 23, 28, 34, 40, 45, ...\r\n\r\nNot once do the leap years meet.\r\n\r\nNow that this is established, are you saying there is no room for either Symmetry454 or Symmetry010 ?\r\nThere is room for them, because they serve different purposes.\r\n\r\nThe Accounting Calendar is \"customisable\", SymmetryXYX is rigid.\r\nThere are, however, structural similarities.\r\n\r\nBoth calendars group \"normal\" years with 364 days, and leap years with 371 days.\r\nIn other words, each year starts on the same week-day and spans either 52 or 53 full weeks on purpose.\r\n\r\nThe Accounting Calendar is available with 12 or 13 months.\r\n\r\nIn the 13-month year each month has exactly 28 days, which has no correspondent in SymmetryXYX.\r\nThe 12-month variant features 8 months of 28 days and 4 months with 35 days, which looks a lot like Symmetry454.\r\n\r\nAn Accounting Calendar may start/end on any month you like, basically.\r\nSymmetryXYX calendars start with January 1st only.\r\n\r\nHowever, the biggest difference is their the leap year formula and occurrence.\r\n\r\n"}}