{"action":"opened","issue":{"url":"https://api.github.com/repos/527897054/FrameFab/issues/45","repository_url":"https://api.github.com/repos/527897054/FrameFab","labels_url":"https://api.github.com/repos/527897054/FrameFab/issues/45/labels{/name}","comments_url":"https://api.github.com/repos/527897054/FrameFab/issues/45/comments","events_url":"https://api.github.com/repos/527897054/FrameFab/issues/45/events","html_url":"https://github.com/527897054/FrameFab/issues/45","id":154169699,"number":45,"title":"\"Not PSD in Hessian Matrix\" in Calculate D","user":{"login":"duckieHuang","id":11905844,"avatar_url":"https://avatars.githubusercontent.com/u/11905844?v=3","gravatar_id":"","url":"https://api.github.com/users/duckieHuang","html_url":"https://github.com/duckieHuang","followers_url":"https://api.github.com/users/duckieHuang/followers","following_url":"https://api.github.com/users/duckieHuang/following{/other_user}","gists_url":"https://api.github.com/users/duckieHuang/gists{/gist_id}","starred_url":"https://api.github.com/users/duckieHuang/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/duckieHuang/subscriptions","organizations_url":"https://api.github.com/users/duckieHuang/orgs","repos_url":"https://api.github.com/users/duckieHuang/repos","events_url":"https://api.github.com/users/duckieHuang/events{/privacy}","received_events_url":"https://api.github.com/users/duckieHuang/received_events","type":"User","site_admin":false},"labels":[{"url":"https://api.github.com/repos/527897054/FrameFab/labels/bug","name":"bug","color":"fc2929"}],"state":"open","locked":false,"assignee":{"login":"duckieHuang","id":11905844,"avatar_url":"https://avatars.githubusercontent.com/u/11905844?v=3","gravatar_id":"","url":"https://api.github.com/users/duckieHuang","html_url":"https://github.com/duckieHuang","followers_url":"https://api.github.com/users/duckieHuang/followers","following_url":"https://api.github.com/users/duckieHuang/following{/other_user}","gists_url":"https://api.github.com/users/duckieHuang/gists{/gist_id}","starred_url":"https://api.github.com/users/duckieHuang/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/duckieHuang/subscriptions","organizations_url":"https://api.github.com/users/duckieHuang/orgs","repos_url":"https://api.github.com/users/duckieHuang/repos","events_url":"https://api.github.com/users/duckieHuang/events{/privacy}","received_events_url":"https://api.github.com/users/duckieHuang/received_events","type":"User","site_admin":false},"milestone":null,"comments":0,"created_at":"2016-05-11T06:32:57Z","updated_at":"2016-05-11T06:32:57Z","closed_at":null,"body":"This should happen because the stiffness matrix is subdivided into two sub-structure, and only the sub-structure is contributing to the matrix.\r\n\r\nSolution:\r\n(1) Add epsilon(K) * I, where I is a 6*Ns_ Square Matrix and epsilon is a small term compared to the average of the diagonal of stiffness matrix K.\r\n\r\n(2) ||d(i)_t||^2 < t_tol^2\r\n      turned to \r\n      x(i) * ||d(i)_t||^2 < t_tol^2\r\nWhen x(i) ->0 , which means that x belongs to top part in current cut, the nodes' constriants is alleviated because it is not in the sub-structure right now.\r\nBut When x(i)->1, the x is likely to be divided to the bottom part, and the constriants should be treated seriously."}}