{"action":"created","issue":{"url":"https://api.github.com/repos/pymor/pymor/issues/103","labels_url":"https://api.github.com/repos/pymor/pymor/issues/103/labels{/name}","comments_url":"https://api.github.com/repos/pymor/pymor/issues/103/comments","events_url":"https://api.github.com/repos/pymor/pymor/issues/103/events","html_url":"https://github.com/pymor/pymor/issues/103","id":58709830,"number":103,"title":"Mass matrix in instationaryDiscretization not identity by default","user":{"login":"fameyer","id":10612604,"avatar_url":"https://avatars.githubusercontent.com/u/10612604?v=3","gravatar_id":"","url":"https://api.github.com/users/fameyer","html_url":"https://github.com/fameyer","followers_url":"https://api.github.com/users/fameyer/followers","following_url":"https://api.github.com/users/fameyer/following{/other_user}","gists_url":"https://api.github.com/users/fameyer/gists{/gist_id}","starred_url":"https://api.github.com/users/fameyer/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/fameyer/subscriptions","organizations_url":"https://api.github.com/users/fameyer/orgs","repos_url":"https://api.github.com/users/fameyer/repos","events_url":"https://api.github.com/users/fameyer/events{/privacy}","received_events_url":"https://api.github.com/users/fameyer/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":2,"created_at":"2015-02-24T08:55:14Z","updated_at":"2015-02-25T13:54:35Z","closed_at":null,"body":"Hello!\r\n\r\nIn the documentation of the InstationaryDiscretization it is said that \r\n\r\n'mass\r\n    The mass Operator M. If None the identity is assumed.' \r\n\r\nBut as far as I see it, when mass=None upon instantiation in my code, mass stays None. Accordingly assertion errors occur later (when doing RB stuff).\r\n\r\nRegards! Falk"},"comment":{"url":"https://api.github.com/repos/pymor/pymor/issues/comments/75962839","html_url":"https://github.com/pymor/pymor/issues/103#issuecomment-75962839","issue_url":"https://api.github.com/repos/pymor/pymor/issues/103","id":75962839,"user":{"login":"fameyer","id":10612604,"avatar_url":"https://avatars.githubusercontent.com/u/10612604?v=3","gravatar_id":"","url":"https://api.github.com/users/fameyer","html_url":"https://github.com/fameyer","followers_url":"https://api.github.com/users/fameyer/followers","following_url":"https://api.github.com/users/fameyer/following{/other_user}","gists_url":"https://api.github.com/users/fameyer/gists{/gist_id}","starred_url":"https://api.github.com/users/fameyer/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/fameyer/subscriptions","organizations_url":"https://api.github.com/users/fameyer/orgs","repos_url":"https://api.github.com/users/fameyer/repos","events_url":"https://api.github.com/users/fameyer/events{/privacy}","received_events_url":"https://api.github.com/users/fameyer/received_events","type":"User","site_admin":false},"created_at":"2015-02-25T13:54:35Z","updated_at":"2015-02-25T13:54:35Z","body":"I define an instationaryDiscretization with some Lincombperators like this:\r\n\r\n`discretizaton = InstationaryDiscretization(operator = op, rhs=rhs, initial_data=u0, T=T, time_stepper = ImplicitEulerTimeStepper(n))`\r\n\r\nSo I do not provide a mass operator. When I now start a greedy search with this discretization I get following error:\r\n\r\n`File \"../pymor/src/pymor/algorithms/timestepping.py\", line 125, in implicit_euler`\r\n`assert isinstance(M,OperatorInterface)`\r\n`AssertionError`\r\n\r\nI debugged it with pdb and up to this point M = None is valid. "}}