{"action":"created","issue":{"url":"https://api.github.com/repos/scipy/scipy/issues/5952","repository_url":"https://api.github.com/repos/scipy/scipy","labels_url":"https://api.github.com/repos/scipy/scipy/issues/5952/labels{/name}","comments_url":"https://api.github.com/repos/scipy/scipy/issues/5952/comments","events_url":"https://api.github.com/repos/scipy/scipy/issues/5952/events","html_url":"https://github.com/scipy/scipy/pull/5952","id":139622624,"number":5952,"title":"Allow for absolute finite difference step","user":{"login":"divenex","id":9269490,"avatar_url":"https://avatars.githubusercontent.com/u/9269490?v=3","gravatar_id":"","url":"https://api.github.com/users/divenex","html_url":"https://github.com/divenex","followers_url":"https://api.github.com/users/divenex/followers","following_url":"https://api.github.com/users/divenex/following{/other_user}","gists_url":"https://api.github.com/users/divenex/gists{/gist_id}","starred_url":"https://api.github.com/users/divenex/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/divenex/subscriptions","organizations_url":"https://api.github.com/users/divenex/orgs","repos_url":"https://api.github.com/users/divenex/repos","events_url":"https://api.github.com/users/divenex/events{/privacy}","received_events_url":"https://api.github.com/users/divenex/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":9,"created_at":"2016-03-09T16:14:35Z","updated_at":"2016-03-10T18:27:57Z","closed_at":null,"pull_request":{"url":"https://api.github.com/repos/scipy/scipy/pulls/5952","html_url":"https://github.com/scipy/scipy/pull/5952","diff_url":"https://github.com/scipy/scipy/pull/5952.diff","patch_url":"https://github.com/scipy/scipy/pull/5952.patch"},"body":"Allow for absolute, rather than only relative, step in the finite difference approximation of the derivatives. \r\n\r\nThis is useful to include an option for **absolute** finite-difference steps in scipy/optimize/_lsq /least_squares.py"},"comment":{"url":"https://api.github.com/repos/scipy/scipy/issues/comments/194990613","html_url":"https://github.com/scipy/scipy/pull/5952#issuecomment-194990613","issue_url":"https://api.github.com/repos/scipy/scipy/issues/5952","id":194990613,"user":{"login":"divenex","id":9269490,"avatar_url":"https://avatars.githubusercontent.com/u/9269490?v=3","gravatar_id":"","url":"https://api.github.com/users/divenex","html_url":"https://github.com/divenex","followers_url":"https://api.github.com/users/divenex/followers","following_url":"https://api.github.com/users/divenex/following{/other_user}","gists_url":"https://api.github.com/users/divenex/gists{/gist_id}","starred_url":"https://api.github.com/users/divenex/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/divenex/subscriptions","organizations_url":"https://api.github.com/users/divenex/orgs","repos_url":"https://api.github.com/users/divenex/repos","events_url":"https://api.github.com/users/divenex/events{/privacy}","received_events_url":"https://api.github.com/users/divenex/received_events","type":"User","site_admin":false},"created_at":"2016-03-10T18:27:57Z","updated_at":"2016-03-10T18:27:57Z","body":"Another common user case where absolute steps are preferred, is when one of the parameters we want to determine from our least squares fit is the position of an event (e.g. particle) in a detector. \r\n\r\nIn this case the chi^2 varies by a similar amount when we change the coordinates by a fixed amount in detector pixels, regardless of the location on the detector. Using relative steps in this case can produce unnecessary orders of magnitude variations in the diff_step, eve tough the step should not depend on the particle position."}}