{"action":"created","issue":{"url":"https://api.github.com/repos/stan-dev/math/issues/33","labels_url":"https://api.github.com/repos/stan-dev/math/issues/33/labels{/name}","comments_url":"https://api.github.com/repos/stan-dev/math/issues/33/comments","events_url":"https://api.github.com/repos/stan-dev/math/issues/33/events","html_url":"https://github.com/stan-dev/math/issues/33","id":93378459,"number":33,"title":"Functions With Improper Derivatives","user":{"login":"syclik","id":425751,"avatar_url":"https://avatars.githubusercontent.com/u/425751?v=3","gravatar_id":"","url":"https://api.github.com/users/syclik","html_url":"https://github.com/syclik","followers_url":"https://api.github.com/users/syclik/followers","following_url":"https://api.github.com/users/syclik/following{/other_user}","gists_url":"https://api.github.com/users/syclik/gists{/gist_id}","starred_url":"https://api.github.com/users/syclik/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/syclik/subscriptions","organizations_url":"https://api.github.com/users/syclik/orgs","repos_url":"https://api.github.com/users/syclik/repos","events_url":"https://api.github.com/users/syclik/events{/privacy}","received_events_url":"https://api.github.com/users/syclik/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":18,"created_at":"2015-07-06T21:12:25Z","updated_at":"2015-07-06T21:12:29Z","closed_at":null,"body":"_From @betanalpha on July 2, 2014 13:2_\n\nRight now the Stan autodiff implements functions with improper derivatives (i.e. the derivatives do not exist at certain points), which is formally improper.  We have seen issues where people use functions like step, floor, and ceil in their models and the resulting sampling is very poor.\r\n\r\nPersonally I'd prefer to limit Stan to functions with proper derivatives only, but in any case we should have the discussion.\n\n_Copied from original issue: stan-dev/stan#731_"},"comment":{"url":"https://api.github.com/repos/stan-dev/math/issues/comments/118999840","html_url":"https://github.com/stan-dev/math/issues/33#issuecomment-118999840","issue_url":"https://api.github.com/repos/stan-dev/math/issues/33","id":118999840,"user":{"login":"syclik","id":425751,"avatar_url":"https://avatars.githubusercontent.com/u/425751?v=3","gravatar_id":"","url":"https://api.github.com/users/syclik","html_url":"https://github.com/syclik","followers_url":"https://api.github.com/users/syclik/followers","following_url":"https://api.github.com/users/syclik/following{/other_user}","gists_url":"https://api.github.com/users/syclik/gists{/gist_id}","starred_url":"https://api.github.com/users/syclik/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/syclik/subscriptions","organizations_url":"https://api.github.com/users/syclik/orgs","repos_url":"https://api.github.com/users/syclik/repos","events_url":"https://api.github.com/users/syclik/events{/privacy}","received_events_url":"https://api.github.com/users/syclik/received_events","type":"User","site_admin":false},"created_at":"2015-07-06T21:12:29Z","updated_at":"2015-07-06T21:12:29Z","body":"_From @betanalpha on July 2, 2014 20:33_\n\nThis is exactly for what I’ve been advocating for some time —\r\ncustom spline, etc functions that exactly enforce the desired\r\nsmoothness properties.\r\n\r\nOn Jul 2, 2014, at 9:18 PM, Bob Carpenter <notifications@github.com> wrote:\r\n\r\n> The one sticking point before was interpolation, but I think \r\n> the answer there may be to write a special BUGS-like interpolation \r\n> function. "}}