{"action":"created","issue":{"url":"https://api.github.com/repos/stan-dev/stan/issues/1536","labels_url":"https://api.github.com/repos/stan-dev/stan/issues/1536/labels{/name}","comments_url":"https://api.github.com/repos/stan-dev/stan/issues/1536/comments","events_url":"https://api.github.com/repos/stan-dev/stan/issues/1536/events","html_url":"https://github.com/stan-dev/stan/issues/1536","id":94202142,"number":1536,"title":"Any chance of adding more general gamma function?","user":{"login":"steven-murray","id":1272030,"avatar_url":"https://avatars.githubusercontent.com/u/1272030?v=3","gravatar_id":"","url":"https://api.github.com/users/steven-murray","html_url":"https://github.com/steven-murray","followers_url":"https://api.github.com/users/steven-murray/followers","following_url":"https://api.github.com/users/steven-murray/following{/other_user}","gists_url":"https://api.github.com/users/steven-murray/gists{/gist_id}","starred_url":"https://api.github.com/users/steven-murray/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/steven-murray/subscriptions","organizations_url":"https://api.github.com/users/steven-murray/orgs","repos_url":"https://api.github.com/users/steven-murray/repos","events_url":"https://api.github.com/users/steven-murray/events{/privacy}","received_events_url":"https://api.github.com/users/steven-murray/received_events","type":"User","site_admin":false},"labels":[{"url":"https://api.github.com/repos/stan-dev/stan/labels/Feature","name":"Feature","color":"84b6eb"}],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":3,"created_at":"2015-07-10T03:07:52Z","updated_at":"2015-07-10T04:20:06Z","closed_at":null,"body":"Hi, \r\n\r\nI am wanting to use the incomplete gamma function, with a negative shape parameter. This is currently not supported by the relevant boost library function. \r\n\r\nTo get around this, I have been trying to artificially increase the slope of my data (a lower-truncated generalised gamma distribution) by weighting each data-point by its value (effectively increases the slope by 1). This means that the Gamma call has a positive shape parameter and is therefore allowed, but introduces other problems (cf. the discussion on the mailing list about weighted log-probabilities). \r\n\r\nIt would be nice to have a more general incomplete gamma function (such a function is implemented for example in GSL, and in mpmath for python). \r\n\r\nThanks\r\nSteven"},"comment":{"url":"https://api.github.com/repos/stan-dev/stan/issues/comments/120221369","html_url":"https://github.com/stan-dev/stan/issues/1536#issuecomment-120221369","issue_url":"https://api.github.com/repos/stan-dev/stan/issues/1536","id":120221369,"user":{"login":"steven-murray","id":1272030,"avatar_url":"https://avatars.githubusercontent.com/u/1272030?v=3","gravatar_id":"","url":"https://api.github.com/users/steven-murray","html_url":"https://github.com/steven-murray","followers_url":"https://api.github.com/users/steven-murray/followers","following_url":"https://api.github.com/users/steven-murray/following{/other_user}","gists_url":"https://api.github.com/users/steven-murray/gists{/gist_id}","starred_url":"https://api.github.com/users/steven-murray/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/steven-murray/subscriptions","organizations_url":"https://api.github.com/users/steven-murray/orgs","repos_url":"https://api.github.com/users/steven-murray/repos","events_url":"https://api.github.com/users/steven-murray/events{/privacy}","received_events_url":"https://api.github.com/users/steven-murray/received_events","type":"User","site_admin":false},"created_at":"2015-07-10T04:20:06Z","updated_at":"2015-07-10T04:20:06Z","body":"Sorry about the math... apparently there is no support for latex in GFM"}}