{"action":"created","issue":{"url":"https://api.github.com/repos/felixlen/trlib/issues/5","repository_url":"https://api.github.com/repos/felixlen/trlib","labels_url":"https://api.github.com/repos/felixlen/trlib/issues/5/labels{/name}","comments_url":"https://api.github.com/repos/felixlen/trlib/issues/5/comments","events_url":"https://api.github.com/repos/felixlen/trlib/issues/5/events","html_url":"https://github.com/felixlen/trlib/issues/5","id":298294974,"number":5,"title":"Issues if gradient and Hessian contain only zeros","user":{"login":"jomi2801","id":12195532,"avatar_url":"https://avatars2.githubusercontent.com/u/12195532?v=4","gravatar_id":"","url":"https://api.github.com/users/jomi2801","html_url":"https://github.com/jomi2801","followers_url":"https://api.github.com/users/jomi2801/followers","following_url":"https://api.github.com/users/jomi2801/following{/other_user}","gists_url":"https://api.github.com/users/jomi2801/gists{/gist_id}","starred_url":"https://api.github.com/users/jomi2801/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/jomi2801/subscriptions","organizations_url":"https://api.github.com/users/jomi2801/orgs","repos_url":"https://api.github.com/users/jomi2801/repos","events_url":"https://api.github.com/users/jomi2801/events{/privacy}","received_events_url":"https://api.github.com/users/jomi2801/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"assignees":[],"milestone":null,"comments":0,"created_at":"2018-02-19T14:29:55Z","updated_at":"2018-02-19T14:34:39Z","closed_at":null,"author_association":"NONE","body":"I have experience some issues with trlib. If I run trlib with zero gradient and Hessian, the result is a NaN vector. Here some code:\r\n```\r\njulia> include(\"/home/johannes/trlib/bindings/julia/trlib.jl\")\r\njulia> using trlib\r\njulia> H = zeros(3, 3); g = zeros(3); radius = 1.0; \r\njulia> TR = trlib.trlib_data(H, g);\r\njulia> trlib.trlib_solve(TR, 1.0);\r\njulia> TR.sol\r\n3-element Array{Float64,1}:\r\n NaN\r\n NaN\r\n NaN\r\n```"},"comment":{"url":"https://api.github.com/repos/felixlen/trlib/issues/comments/366710481","html_url":"https://github.com/felixlen/trlib/issues/5#issuecomment-366710481","issue_url":"https://api.github.com/repos/felixlen/trlib/issues/5","id":366710481,"user":{"login":"felixlen","id":977688,"avatar_url":"https://avatars3.githubusercontent.com/u/977688?v=4","gravatar_id":"","url":"https://api.github.com/users/felixlen","html_url":"https://github.com/felixlen","followers_url":"https://api.github.com/users/felixlen/followers","following_url":"https://api.github.com/users/felixlen/following{/other_user}","gists_url":"https://api.github.com/users/felixlen/gists{/gist_id}","starred_url":"https://api.github.com/users/felixlen/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/felixlen/subscriptions","organizations_url":"https://api.github.com/users/felixlen/orgs","repos_url":"https://api.github.com/users/felixlen/repos","events_url":"https://api.github.com/users/felixlen/events{/privacy}","received_events_url":"https://api.github.com/users/felixlen/received_events","type":"User","site_admin":false},"created_at":"2018-02-19T14:34:39Z","updated_at":"2018-02-19T14:34:39Z","author_association":"OWNER","body":"Please note that the method is iterative and thus searches solutions in the Krylov subspace generated from the hessian and gradient consisting of powers of the hessian applied to the gradient. That subspace is zero in the case of zero hessian and gradient and your trivial example is not any meaningful input for the algorithm. I will add a test to handle this very special case."}}
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