{"action":"created","issue":{"url":"https://api.github.com/repos/astropy/astropy/issues/3548","labels_url":"https://api.github.com/repos/astropy/astropy/issues/3548/labels{/name}","comments_url":"https://api.github.com/repos/astropy/astropy/issues/3548/comments","events_url":"https://api.github.com/repos/astropy/astropy/issues/3548/events","html_url":"https://github.com/astropy/astropy/pull/3548","id":58967838,"number":3548,"title":"Rotate by matrix","user":{"login":"nden","id":1110361,"avatar_url":"https://avatars.githubusercontent.com/u/1110361?v=3","gravatar_id":"","url":"https://api.github.com/users/nden","html_url":"https://github.com/nden","followers_url":"https://api.github.com/users/nden/followers","following_url":"https://api.github.com/users/nden/following{/other_user}","gists_url":"https://api.github.com/users/nden/gists{/gist_id}","starred_url":"https://api.github.com/users/nden/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/nden/subscriptions","organizations_url":"https://api.github.com/users/nden/orgs","repos_url":"https://api.github.com/users/nden/repos","events_url":"https://api.github.com/users/nden/events{/privacy}","received_events_url":"https://api.github.com/users/nden/received_events","type":"User","site_admin":false},"labels":[{"url":"https://api.github.com/repos/astropy/astropy/labels/modeling","name":"modeling","color":"c7def8"}],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":7,"created_at":"2015-02-25T20:53:37Z","updated_at":"2015-02-26T16:09:06Z","closed_at":null,"pull_request":{"url":"https://api.github.com/repos/astropy/astropy/pulls/3548","html_url":"https://github.com/astropy/astropy/pull/3548","diff_url":"https://github.com/astropy/astropy/pull/3548.diff","patch_url":"https://github.com/astropy/astropy/pull/3548.patch"},"body":"`modeling.Rotation2D` takes an angle as a parameter. There are many use cases for a model which takes as a parameter a rotation matrix and `AffineTransformation2D` is sometimes too inconvenient to use for this purpose. I am proposing adding back the functionality as a separate model which performs only a rotation. I'll add a test if this is accepted.\r\n\r\n@embray @mhvk "},"comment":{"url":"https://api.github.com/repos/astropy/astropy/issues/comments/76205704","html_url":"https://github.com/astropy/astropy/pull/3548#issuecomment-76205704","issue_url":"https://api.github.com/repos/astropy/astropy/issues/3548","id":76205704,"user":{"login":"nden","id":1110361,"avatar_url":"https://avatars.githubusercontent.com/u/1110361?v=3","gravatar_id":"","url":"https://api.github.com/users/nden","html_url":"https://github.com/nden","followers_url":"https://api.github.com/users/nden/followers","following_url":"https://api.github.com/users/nden/following{/other_user}","gists_url":"https://api.github.com/users/nden/gists{/gist_id}","starred_url":"https://api.github.com/users/nden/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/nden/subscriptions","organizations_url":"https://api.github.com/users/nden/orgs","repos_url":"https://api.github.com/users/nden/repos","events_url":"https://api.github.com/users/nden/events{/privacy}","received_events_url":"https://api.github.com/users/nden/received_events","type":"User","site_admin":false},"created_at":"2015-02-26T16:09:06Z","updated_at":"2015-02-26T16:09:06Z","body":"@mdboom Yes, you are right. \r\nI am looking at this from the FITS WCS point of view, where a typical transformation is defined as shift/rotate/skew. This can be implemented as a compound model `Shift | AffineTransformation2D`, where the affine transformation has no translation. But I am wondering if it won't be more convenient and less confusing to users to have a dedicated model which does only the matrix part. \r\n\r\n"}}