{"action":"created","issue":{"url":"https://api.github.com/repos/OPM/opm-autodiff/issues/357","labels_url":"https://api.github.com/repos/OPM/opm-autodiff/issues/357/labels{/name}","comments_url":"https://api.github.com/repos/OPM/opm-autodiff/issues/357/comments","events_url":"https://api.github.com/repos/OPM/opm-autodiff/issues/357/events","html_url":"https://github.com/OPM/opm-autodiff/issues/357","id":68605567,"number":357,"title":"Sparsity pattern of matrix in CPR preconditioner unsymmetric for large time steps.","user":{"login":"blattms","id":1944640,"avatar_url":"https://avatars.githubusercontent.com/u/1944640?v=3","gravatar_id":"","url":"https://api.github.com/users/blattms","html_url":"https://github.com/blattms","followers_url":"https://api.github.com/users/blattms/followers","following_url":"https://api.github.com/users/blattms/following{/other_user}","gists_url":"https://api.github.com/users/blattms/gists{/gist_id}","starred_url":"https://api.github.com/users/blattms/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/blattms/subscriptions","organizations_url":"https://api.github.com/users/blattms/orgs","repos_url":"https://api.github.com/users/blattms/repos","events_url":"https://api.github.com/users/blattms/events{/privacy}","received_events_url":"https://api.github.com/users/blattms/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"milestone":{"url":"https://api.github.com/repos/OPM/opm-autodiff/milestones/2","html_url":"https://github.com/OPM/opm-autodiff/milestones/Release%202015.10","labels_url":"https://api.github.com/repos/OPM/opm-autodiff/milestones/2/labels","id":1037814,"number":2,"title":"Release 2015.10","description":"","creator":{"login":"atgeirr","id":1876621,"avatar_url":"https://avatars.githubusercontent.com/u/1876621?v=3","gravatar_id":"","url":"https://api.github.com/users/atgeirr","html_url":"https://github.com/atgeirr","followers_url":"https://api.github.com/users/atgeirr/followers","following_url":"https://api.github.com/users/atgeirr/following{/other_user}","gists_url":"https://api.github.com/users/atgeirr/gists{/gist_id}","starred_url":"https://api.github.com/users/atgeirr/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/atgeirr/subscriptions","organizations_url":"https://api.github.com/users/atgeirr/orgs","repos_url":"https://api.github.com/users/atgeirr/repos","events_url":"https://api.github.com/users/atgeirr/events{/privacy}","received_events_url":"https://api.github.com/users/atgeirr/received_events","type":"User","site_admin":false},"open_issues":7,"closed_issues":4,"state":"open","created_at":"2015-03-25T09:03:34Z","updated_at":"2015-10-08T13:00:05Z","due_on":"2015-10-26T23:00:00Z","closed_at":null},"comments":5,"created_at":"2015-04-15T07:49:23Z","updated_at":"2015-10-08T13:01:53Z","closed_at":null,"body":"This bug was actually posted for DUNE by @dr-robertk, see https://dune-project.org/flyspray/index.php?do=details&task_id=1608. But I think the problem is not in DUNE but in the way the discretization matrices are constructed (and optimized) in OPM.\r\n\r\nThe cause for the error:\r\n```\r\nISTLError [operator[]:dune-istl/dune/istl/basearray.hh:587]: index 1118 not in compressed array terminate called after throwing an instance of 'Dune::ISTLError\r\n```\r\nis that the more powerful coarsen criteria used to compute the aggregation and the coarse matrix assume that if the sparse matrix stores a value at (i,j) then it also stores a value at (j,i) (I call this a symmetric sparsity pattern). Actually this should be the case for the matrices in flow, too. But some time ago a an optimization was introduced  that skips small values and does not store them to reduce the number of non-zeros. I am under the impression that this produces some missing values and renders the sparsity pattern unsymmetric."},"comment":{"url":"https://api.github.com/repos/OPM/opm-autodiff/issues/comments/146535861","html_url":"https://github.com/OPM/opm-autodiff/issues/357#issuecomment-146535861","issue_url":"https://api.github.com/repos/OPM/opm-autodiff/issues/357","id":146535861,"user":{"login":"atgeirr","id":1876621,"avatar_url":"https://avatars.githubusercontent.com/u/1876621?v=3","gravatar_id":"","url":"https://api.github.com/users/atgeirr","html_url":"https://github.com/atgeirr","followers_url":"https://api.github.com/users/atgeirr/followers","following_url":"https://api.github.com/users/atgeirr/following{/other_user}","gists_url":"https://api.github.com/users/atgeirr/gists{/gist_id}","starred_url":"https://api.github.com/users/atgeirr/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/atgeirr/subscriptions","organizations_url":"https://api.github.com/users/atgeirr/orgs","repos_url":"https://api.github.com/users/atgeirr/repos","events_url":"https://api.github.com/users/atgeirr/events{/privacy}","received_events_url":"https://api.github.com/users/atgeirr/received_events","type":"User","site_admin":false},"created_at":"2015-10-08T13:01:53Z","updated_at":"2015-10-08T13:01:53Z","body":"> It seems that the CPR preconditioner has fallen from grace and currently it's not clear if it's still in use.\r\n\r\nWhile it is not currently the fastest way to run Norne, I am pretty confident it may be competitive for larger cases. While postponing again is less than ideal, it's ok with me (reminds us that we should look at it eventually)."}}