{"action":"created","issue":{"url":"https://api.github.com/repos/poliastro/poliastro/issues/328","repository_url":"https://api.github.com/repos/poliastro/poliastro","labels_url":"https://api.github.com/repos/poliastro/poliastro/issues/328/labels{/name}","comments_url":"https://api.github.com/repos/poliastro/poliastro/issues/328/comments","events_url":"https://api.github.com/repos/poliastro/poliastro/issues/328/events","html_url":"https://github.com/poliastro/poliastro/issues/328","id":300786032,"number":328,"title":"Using other propagation methods for propagating the orbit through Orbit.Sample()","user":{"login":"shreyasbapat","id":24257914,"avatar_url":"https://avatars0.githubusercontent.com/u/24257914?v=4","gravatar_id":"","url":"https://api.github.com/users/shreyasbapat","html_url":"https://github.com/shreyasbapat","followers_url":"https://api.github.com/users/shreyasbapat/followers","following_url":"https://api.github.com/users/shreyasbapat/following{/other_user}","gists_url":"https://api.github.com/users/shreyasbapat/gists{/gist_id}","starred_url":"https://api.github.com/users/shreyasbapat/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/shreyasbapat/subscriptions","organizations_url":"https://api.github.com/users/shreyasbapat/orgs","repos_url":"https://api.github.com/users/shreyasbapat/repos","events_url":"https://api.github.com/users/shreyasbapat/events{/privacy}","received_events_url":"https://api.github.com/users/shreyasbapat/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"assignees":[],"milestone":null,"comments":3,"created_at":"2018-02-27T20:44:51Z","updated_at":"2018-02-28T14:46:30Z","closed_at":null,"author_association":"CONTRIBUTOR","body":"<!--- Provide a general summary of the issue in the Title above -->\r\nCurrently we can only use the basic ```mean_method``` function to propagate orbits. As the Orbit.Sample() can now accept other propagators as well, we must be able to use ```cowell``` method  as well.\r\n🐞 **Problem**\r\nWe can't use the cowell's method and other propagators to propagate the orbit because of differences in the parameters passed in the normal propagator while using Orbit.Sample().\r\n<!--- Provide a detailed description of the change or addition you are proposing -->\r\n<!--- If it is a feature or a bug, what problem is it solving-->\r\n\r\n🖥 **Please paste the output of following commands**\r\n\r\n`conda info -a`\r\n\r\n`python -c \"import poliastro.testing; poliastro.testing.test()\"`\r\npython3 -c \"import poliastro.testing; poliastro.testing.test()\"\r\n============================= test session starts ==============================\r\nplatform linux -- Python 3.6.3, pytest-3.4.1, py-1.5.2, pluggy-0.6.0\r\nrootdir: /home/shreyas/poliastro, inifile: setup.cfg\r\nplugins: cov-2.5.1\r\ncollected 141 items                                                            \r\n\r\npoliastro/src/poliastro/tests/test_bodies.py ......                      [  4%]\r\npoliastro/src/poliastro/tests/test_coordinates.py ...                    [  6%]\r\npoliastro/src/poliastro/tests/test_hyper.py ...........                  [ 14%]\r\npoliastro/src/poliastro/tests/test_iod.py .........                      [ 20%]\r\npoliastro/src/poliastro/tests/test_jit.py ...                            [ 22%]\r\npoliastro/src/poliastro/tests/test_maneuver.py ......                    [ 26%]\r\npoliastro/src/poliastro/tests/test_patched_conics.py ..                  [ 28%]\r\npoliastro/src/poliastro/tests/test_plotting.py .........                 [ 34%]\r\npoliastro/src/poliastro/tests/test_plotting3d.py ......                  [ 39%]\r\npoliastro/src/poliastro/tests/test_stumpff.py ...                        [ 41%]\r\npoliastro/src/poliastro/tests/test_twobody.py ..                         [ 42%]\r\npoliastro/src/poliastro/tests/test_util.py .......                       [ 47%]\r\npoliastro/src/poliastro/tests/tests_neos/test_dastcom5.py .........      [ 53%]\r\npoliastro/src/poliastro/tests/tests_neos/test_neos_neows.py ......       [ 58%]\r\npoliastro/src/poliastro/tests/tests_twobody/test_angles.py .......       [ 63%]\r\npoliastro/src/poliastro/tests/tests_twobody/test_decorators.py ..        [ 64%]\r\npoliastro/src/poliastro/tests/tests_twobody/test_orbit.py .............. [ 74%]\r\n.....                                                                    [ 78%]\r\npoliastro/src/poliastro/tests/tests_twobody/test_propagation.py ........ [ 83%]\r\n.                                                                        [ 84%]\r\npoliastro/src/poliastro/tests/tests_twobody/test_sample.py ............  [ 92%]\r\npoliastro/src/poliastro/tests/tests_twobody/test_states.py ..........    [100%]\r\n\r\n========================= 141 passed in 21.47 seconds ==========================\r\n\r\n🎯 **Goal**\r\nTo be able to Propagate the orbit using different propagators.\r\n<!--- Why is this change important to you? How would you use it? -->\r\n<!--- How can it benefit other users? -->\r\n\r\n💡 **Possible solutions**\r\n<!--- Not obligatory, but suggest an idea for implementing addition or change -->\r\n\r\n📋  **Steps to solve the problem**\r\n\r\n * Comment below about what you've started working on.\r\n * Add, commit, push your changes\r\n * Submit a pull request and add this in comments - `Addresses #<put issue number here>`\r\n * Ask for a review in comments section of pull request\r\n * Celebrate your contribution to this project 🎉 \r\n"},"comment":{"url":"https://api.github.com/repos/poliastro/poliastro/issues/comments/369261572","html_url":"https://github.com/poliastro/poliastro/issues/328#issuecomment-369261572","issue_url":"https://api.github.com/repos/poliastro/poliastro/issues/328","id":369261572,"user":{"login":"Juanlu001","id":316517,"avatar_url":"https://avatars2.githubusercontent.com/u/316517?v=4","gravatar_id":"","url":"https://api.github.com/users/Juanlu001","html_url":"https://github.com/Juanlu001","followers_url":"https://api.github.com/users/Juanlu001/followers","following_url":"https://api.github.com/users/Juanlu001/following{/other_user}","gists_url":"https://api.github.com/users/Juanlu001/gists{/gist_id}","starred_url":"https://api.github.com/users/Juanlu001/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/Juanlu001/subscriptions","organizations_url":"https://api.github.com/users/Juanlu001/orgs","repos_url":"https://api.github.com/users/Juanlu001/repos","events_url":"https://api.github.com/users/Juanlu001/events{/privacy}","received_events_url":"https://api.github.com/users/Juanlu001/received_events","type":"User","site_admin":false},"created_at":"2018-02-28T14:46:30Z","updated_at":"2018-02-28T14:46:30Z","author_association":"OWNER","body":"This looks like a convergence problem with the `cowell` method, rather than an API problem:\r\n\r\n```\r\nIn [25]: iss.propagate(0 * u.s, method=cowell)\r\n/home/juanlu/.miniconda36/envs/poliastro36/lib/python3.6/site-packages/scipy/integrate/_ode.py:1095: UserWarning: dop853: step size becomes too small\r\n  self.messages.get(istate, unexpected_istate_msg)))\r\n---------------------------------------------------------------------------\r\nRuntimeError                              Traceback (most recent call last)\r\n<ipython-input-25-5ec3bbe8e578> in <module>()\r\n----> 1 iss.propagate(0 * u.s, method=cowell)\r\n\r\n~/Development/poliastro/poliastro-library/src/poliastro/twobody/orbit.py in propagate(self, epoch_or_duration, method, rtol)\r\n    254             time_of_flight = time.TimeDelta(epoch_or_duration)\r\n    255 \r\n--> 256         return propagate(self, time_of_flight, method=method, rtol=rtol)\r\n    257 \r\n    258     def sample(self, values=None, method=mean_motion):\r\n\r\n~/Development/poliastro/poliastro-library/src/poliastro/twobody/propagation.py in propagate(orbit, time_of_flight, method, rtol, **kwargs)\r\n    213                   time_of_flight.to(u.s).value,\r\n    214                   rtol=rtol,\r\n--> 215                   **kwargs)\r\n    216     return orbit.from_vectors(orbit.attractor, r * u.km, v * u.km / u.s, orbit.epoch + time_of_flight)\r\n    217 \r\n\r\n~/Development/poliastro/poliastro-library/src/poliastro/twobody/propagation.py in cowell(k, r0, v0, tof, rtol, ad, callback, nsteps)\r\n    102         r, v = rr.y[:3], rr.y[3:]\r\n    103     else:\r\n--> 104         raise RuntimeError(\"Integration failed\")\r\n    105 \r\n    106     return r, v\r\n\r\nRuntimeError: Integration failed\r\n```\r\n\r\nof course, sending a value of 0 seconds should return just the same position :) An easy issue to fix!"}}
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