{"action":"opened","issue":{"url":"https://api.github.com/repos/chebfun/chebfun/issues/1890","repository_url":"https://api.github.com/repos/chebfun/chebfun","labels_url":"https://api.github.com/repos/chebfun/chebfun/issues/1890/labels{/name}","comments_url":"https://api.github.com/repos/chebfun/chebfun/issues/1890/comments","events_url":"https://api.github.com/repos/chebfun/chebfun/issues/1890/events","html_url":"https://github.com/chebfun/chebfun/issues/1890","id":154583496,"number":1890,"title":"chebfun/vectorCheck","user":{"login":"lsfinn","id":920237,"avatar_url":"https://avatars.githubusercontent.com/u/920237?v=3","gravatar_id":"","url":"https://api.github.com/users/lsfinn","html_url":"https://github.com/lsfinn","followers_url":"https://api.github.com/users/lsfinn/followers","following_url":"https://api.github.com/users/lsfinn/following{/other_user}","gists_url":"https://api.github.com/users/lsfinn/gists{/gist_id}","starred_url":"https://api.github.com/users/lsfinn/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/lsfinn/subscriptions","organizations_url":"https://api.github.com/users/lsfinn/orgs","repos_url":"https://api.github.com/users/lsfinn/repos","events_url":"https://api.github.com/users/lsfinn/events{/privacy}","received_events_url":"https://api.github.com/users/lsfinn/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":0,"created_at":"2016-05-12T21:16:39Z","updated_at":"2016-05-12T21:16:39Z","closed_at":null,"body":"vectorCheck aims to evaluate the op on a slightly smaller domain to avoid endpoint problems; however, it appears to reflect something half-implemented, which will fail for a domain with a zero endpoint. \r\n\r\n```matlab\r\ndel = diff(y)/200;\r\nif ( y(1) > 0 )\r\n    y(1) = (1+del)*y(1); \r\nelse\r\n    y(1) = (1-del)*y(1); \r\nend\r\n\r\nif ( y(end) > 0 )\r\n    y(end) = (1-del)*y(end); \r\nelse\r\n    y(end) = (1+del)*y(end); \r\nend\r\n```\r\n\r\nwhere `y` is the domain. More than likely what was intended here is \r\n\r\n```matlab\r\ndel = diff(y)/200;\r\ny(1) = y(1) + del;\r\ny(end) = y(end) - del;\r\n```\r\n"}}