{"action":"created","issue":{"url":"https://api.github.com/repos/firedrakeproject/firedrake/issues/436","labels_url":"https://api.github.com/repos/firedrakeproject/firedrake/issues/436/labels{/name}","comments_url":"https://api.github.com/repos/firedrakeproject/firedrake/issues/436/comments","events_url":"https://api.github.com/repos/firedrakeproject/firedrake/issues/436/events","html_url":"https://github.com/firedrakeproject/firedrake/issues/436","id":55283462,"number":436,"title":"More coffee optimiser failures","user":{"login":"wence-","id":1126981,"avatar_url":"https://avatars.githubusercontent.com/u/1126981?v=3","gravatar_id":"","url":"https://api.github.com/users/wence-","html_url":"https://github.com/wence-","followers_url":"https://api.github.com/users/wence-/followers","following_url":"https://api.github.com/users/wence-/following{/other_user}","gists_url":"https://api.github.com/users/wence-/gists{/gist_id}","starred_url":"https://api.github.com/users/wence-/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/wence-/subscriptions","organizations_url":"https://api.github.com/users/wence-/orgs","repos_url":"https://api.github.com/users/wence-/repos","events_url":"https://api.github.com/users/wence-/events{/privacy}","received_events_url":"https://api.github.com/users/wence-/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":1,"created_at":"2015-01-23T13:54:38Z","updated_at":"2015-01-26T14:28:46Z","closed_at":null,"body":"Here's a stripped down version of the problem in #425.  The error is in the assembly of the diagonal A00 block.  With coffee switched on, the SVD of the operator is completely different.\r\n\r\n```python\r\nfrom firedrake import *\r\nmesh = UnitSquareMesh(2, 2)\r\n\r\nU = VectorFunctionSpace(mesh, \"CG\", 2)\r\n\r\nu = Function(U)\r\nw = TestFunction(U)\r\n\r\ndt = 0.5\r\nu_old = Function(U)\r\nF = 0\r\nM_momentum = (1.0/dt)*(inner(w, u) - inner(w, u_old))*dx\r\nF += M_momentum\r\n\r\nA_momentum = inner(dot(grad(u), u), w)*dx\r\nF += A_momentum\r\n\r\n# viscosity = Constant(0.7)\r\n# K_momentum = -viscosity*inner(grad(u) + grad(u).T, grad(w))*dx\r\n# F -= K_momentum\r\n\r\nparameters[\"coffee\"][\"O2\"] = False\r\na = derivative(F, u)\r\nA = assemble(a)\r\n\r\nimport numpy as np\r\n\r\nu, s, v = np.linalg.svd(A.M.values)\r\n\r\nprint s[:8]\r\n```\r\n\r\nNote this also fails with VFS degree 1, but this is closer to the original problem."},"comment":{"url":"https://api.github.com/repos/firedrakeproject/firedrake/issues/comments/71468092","html_url":"https://github.com/firedrakeproject/firedrake/issues/436#issuecomment-71468092","issue_url":"https://api.github.com/repos/firedrakeproject/firedrake/issues/436","id":71468092,"user":{"login":"FabioLuporini","id":478143,"avatar_url":"https://avatars.githubusercontent.com/u/478143?v=3","gravatar_id":"","url":"https://api.github.com/users/FabioLuporini","html_url":"https://github.com/FabioLuporini","followers_url":"https://api.github.com/users/FabioLuporini/followers","following_url":"https://api.github.com/users/FabioLuporini/following{/other_user}","gists_url":"https://api.github.com/users/FabioLuporini/gists{/gist_id}","starred_url":"https://api.github.com/users/FabioLuporini/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/FabioLuporini/subscriptions","organizations_url":"https://api.github.com/users/FabioLuporini/orgs","repos_url":"https://api.github.com/users/FabioLuporini/repos","events_url":"https://api.github.com/users/FabioLuporini/events{/privacy}","received_events_url":"https://api.github.com/users/FabioLuporini/received_events","type":"User","site_admin":false},"created_at":"2015-01-26T14:28:46Z","updated_at":"2015-01-26T14:28:46Z","body":"Branch fix-issue-436-firedrake in COFFEE should fix the issue. Please, let me know if you agree with this. All tests seem to pass; so if reasonable to you, @wence-, I'll merge"}}