{"action":"created","issue":{"url":"https://api.github.com/repos/drhagen/scipy_ode/issues/3","repository_url":"https://api.github.com/repos/drhagen/scipy_ode","labels_url":"https://api.github.com/repos/drhagen/scipy_ode/issues/3/labels{/name}","comments_url":"https://api.github.com/repos/drhagen/scipy_ode/issues/3/comments","events_url":"https://api.github.com/repos/drhagen/scipy_ode/issues/3/events","html_url":"https://github.com/drhagen/scipy_ode/issues/3","id":173434397,"number":3,"title":"scipy.interpolate.PPoly becomes numerically unstable for high order","user":{"login":"aarchiba","id":136867,"avatar_url":"https://avatars.githubusercontent.com/u/136867?v=3","gravatar_id":"","url":"https://api.github.com/users/aarchiba","html_url":"https://github.com/aarchiba","followers_url":"https://api.github.com/users/aarchiba/followers","following_url":"https://api.github.com/users/aarchiba/following{/other_user}","gists_url":"https://api.github.com/users/aarchiba/gists{/gist_id}","starred_url":"https://api.github.com/users/aarchiba/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/aarchiba/subscriptions","organizations_url":"https://api.github.com/users/aarchiba/orgs","repos_url":"https://api.github.com/users/aarchiba/repos","events_url":"https://api.github.com/users/aarchiba/events{/privacy}","received_events_url":"https://api.github.com/users/aarchiba/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"assignees":[],"milestone":null,"comments":5,"created_at":"2016-08-26T11:43:31Z","updated_at":"2016-08-27T17:35:26Z","closed_at":null,"body":"The Bulirsch-Stoer integrator can easily produce dense-output polynomials of order higher than 20. This is known to be a problem if you represent them in the power basis, as scipy.interpolate.PPoly does. scipy.interpolate.KroghInterpolator uses an algorithm that is considerablye more stable, numerically. So forcing solvers to output a PPoly \"spline\" is a numerical problem. Perhaps it would be easier if the solver simply provided a callable for each step, which OdeSolution could then forward calls to?"},"comment":{"url":"https://api.github.com/repos/drhagen/scipy_ode/issues/comments/242930251","html_url":"https://github.com/drhagen/scipy_ode/issues/3#issuecomment-242930251","issue_url":"https://api.github.com/repos/drhagen/scipy_ode/issues/3","id":242930251,"user":{"login":"drhagen","id":2952478,"avatar_url":"https://avatars.githubusercontent.com/u/2952478?v=3","gravatar_id":"","url":"https://api.github.com/users/drhagen","html_url":"https://github.com/drhagen","followers_url":"https://api.github.com/users/drhagen/followers","following_url":"https://api.github.com/users/drhagen/following{/other_user}","gists_url":"https://api.github.com/users/drhagen/gists{/gist_id}","starred_url":"https://api.github.com/users/drhagen/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/drhagen/subscriptions","organizations_url":"https://api.github.com/users/drhagen/orgs","repos_url":"https://api.github.com/users/drhagen/repos","events_url":"https://api.github.com/users/drhagen/events{/privacy}","received_events_url":"https://api.github.com/users/drhagen/received_events","type":"User","site_admin":false},"created_at":"2016-08-27T17:35:26Z","updated_at":"2016-08-27T17:35:26Z","body":"I have already renamed it locally to `interpolator`.\r\n\r\nBoth of the alternatives you mention could be done. If there is any kind of setup cost for the interpolator, both of those will be a lot slower. The list of interpolators will require thousands of small setups. The evaluation method would require setting up the interpolator each time points are requested. But I don't know if the setup cost is meaningful, so those remain valid alternatives."}}
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