{"action":"created","issue":{"url":"https://api.github.com/repos/numba/numba/issues/1251","labels_url":"https://api.github.com/repos/numba/numba/issues/1251/labels{/name}","comments_url":"https://api.github.com/repos/numba/numba/issues/1251/comments","events_url":"https://api.github.com/repos/numba/numba/issues/1251/events","html_url":"https://github.com/numba/numba/issues/1251","id":90176059,"number":1251,"title":"simpler example of nopython decorated function returning different results than python implementation","user":{"login":"bmer","id":4350451,"avatar_url":"https://avatars.githubusercontent.com/u/4350451?v=3","gravatar_id":"","url":"https://api.github.com/users/bmer","html_url":"https://github.com/bmer","followers_url":"https://api.github.com/users/bmer/followers","following_url":"https://api.github.com/users/bmer/following{/other_user}","gists_url":"https://api.github.com/users/bmer/gists{/gist_id}","starred_url":"https://api.github.com/users/bmer/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/bmer/subscriptions","organizations_url":"https://api.github.com/users/bmer/orgs","repos_url":"https://api.github.com/users/bmer/repos","events_url":"https://api.github.com/users/bmer/events{/privacy}","received_events_url":"https://api.github.com/users/bmer/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":2,"created_at":"2015-06-22T18:38:09Z","updated_at":"2015-06-22T18:47:14Z","closed_at":null,"body":"Previously, [I created an issue that might be related](https://github.com/numba/numba/issues/1249) (at the very least, the symptoms of the problem are the same), but it had a more complicated example script. Here, I present a much simpler example script: https://gist.github.com/bmer/9d3c445cc3cb3c65930f\r\n\r\nThe script generates a simple polygon, and then calculates \"edge vectors\", and prints a numpy generated comparison of both results. We see that the numba calculated results are different from the python calculated results, but only in the \"y\" column:\r\n\r\n```\r\n[[ True False]\r\n [ True False]\r\n [ True False]\r\n [ True False]\r\n [ True False]\r\n [ True False]\r\n [ True False]\r\n [ True False]\r\n [ True False]\r\n [ True False]]\r\n```"},"comment":{"url":"https://api.github.com/repos/numba/numba/issues/comments/114216448","html_url":"https://github.com/numba/numba/issues/1251#issuecomment-114216448","issue_url":"https://api.github.com/repos/numba/numba/issues/1251","id":114216448,"user":{"login":"pitrou","id":1721820,"avatar_url":"https://avatars.githubusercontent.com/u/1721820?v=3","gravatar_id":"","url":"https://api.github.com/users/pitrou","html_url":"https://github.com/pitrou","followers_url":"https://api.github.com/users/pitrou/followers","following_url":"https://api.github.com/users/pitrou/following{/other_user}","gists_url":"https://api.github.com/users/pitrou/gists{/gist_id}","starred_url":"https://api.github.com/users/pitrou/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/pitrou/subscriptions","organizations_url":"https://api.github.com/users/pitrou/orgs","repos_url":"https://api.github.com/users/pitrou/repos","events_url":"https://api.github.com/users/pitrou/events{/privacy}","received_events_url":"https://api.github.com/users/pitrou/received_events","type":"User","site_admin":false},"created_at":"2015-06-22T18:47:14Z","updated_at":"2015-06-22T18:47:14Z","body":"It seems tuple unpacking on array views is faulty. If you replace the inner assignment with:\r\n```\r\n        xA = node_coords[i,0]\r\n        yA = node_coords[i,1]\r\n        xB = node_coords[i_plus1,0]\r\n        yB = node_coords[i_plus1,1]\r\n```\r\n\r\nthen the problem disappears."}}