{"action":"created","issue":{"url":"https://api.github.com/repos/davidsblom/FOAM-FSI/issues/78","labels_url":"https://api.github.com/repos/davidsblom/FOAM-FSI/issues/78/labels{/name}","comments_url":"https://api.github.com/repos/davidsblom/FOAM-FSI/issues/78/comments","events_url":"https://api.github.com/repos/davidsblom/FOAM-FSI/issues/78/events","html_url":"https://github.com/davidsblom/FOAM-FSI/issues/78","id":92188364,"number":78,"title":"problem with WendlandC6. If all points are used, error is larger than machine precision","user":{"login":"thijsgillebaart","id":6001811,"avatar_url":"https://avatars.githubusercontent.com/u/6001811?v=3","gravatar_id":"","url":"https://api.github.com/users/thijsgillebaart","html_url":"https://github.com/thijsgillebaart","followers_url":"https://api.github.com/users/thijsgillebaart/followers","following_url":"https://api.github.com/users/thijsgillebaart/following{/other_user}","gists_url":"https://api.github.com/users/thijsgillebaart/gists{/gist_id}","starred_url":"https://api.github.com/users/thijsgillebaart/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/thijsgillebaart/subscriptions","organizations_url":"https://api.github.com/users/thijsgillebaart/orgs","repos_url":"https://api.github.com/users/thijsgillebaart/repos","events_url":"https://api.github.com/users/thijsgillebaart/events{/privacy}","received_events_url":"https://api.github.com/users/thijsgillebaart/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":5,"created_at":"2015-06-30T20:11:54Z","updated_at":"2015-07-01T08:14:23Z","closed_at":null,"body":"Not fully tested yet, but not working properly."},"comment":{"url":"https://api.github.com/repos/davidsblom/FOAM-FSI/issues/comments/117526600","html_url":"https://github.com/davidsblom/FOAM-FSI/issues/78#issuecomment-117526600","issue_url":"https://api.github.com/repos/davidsblom/FOAM-FSI/issues/78","id":117526600,"user":{"login":"davidsblom","id":49148,"avatar_url":"https://avatars.githubusercontent.com/u/49148?v=3","gravatar_id":"","url":"https://api.github.com/users/davidsblom","html_url":"https://github.com/davidsblom","followers_url":"https://api.github.com/users/davidsblom/followers","following_url":"https://api.github.com/users/davidsblom/following{/other_user}","gists_url":"https://api.github.com/users/davidsblom/gists{/gist_id}","starred_url":"https://api.github.com/users/davidsblom/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/davidsblom/subscriptions","organizations_url":"https://api.github.com/users/davidsblom/orgs","repos_url":"https://api.github.com/users/davidsblom/repos","events_url":"https://api.github.com/users/davidsblom/events{/privacy}","received_events_url":"https://api.github.com/users/davidsblom/received_events","type":"User","site_admin":false},"created_at":"2015-07-01T08:14:22Z","updated_at":"2015-07-01T08:14:22Z","body":"I've created a python script to see what the difference is, and it appears that the functions are described by Rendall and Allen are the same functions, except for the scaling constant.\r\nThe C6 functions are up to an error 1.0e-16 exactly the same, so machine precision.\r\n\r\n``` python\r\n#!/usr/bin/env python\r\n\r\nimport matplotlib.pyplot as plt\r\nimport numpy as np\r\n\r\ny1 = np.zeros( 101 )\r\ny2 = np.zeros( 101 )\r\nx = np.zeros( 101 )\r\n\r\nfor i in np.arange( 101 ):\r\n    x[i] = i / 101.0\r\n    r = x[i]\r\n    y1[i] = np.power( 1.0 - r, 8.0 ) * ( 15.0 + 120.0*r + 375.0*r*r + 480.0*np.power(r,3) ) / 332640.0\r\n    y2[i] = np.power( 1.0 - r, 8.0 ) * ( 1.0 + 8.0*r + 25.0*r*r + 32.0*np.power(r,3) )\r\n\r\ny1 /= y1[0]\r\n\r\nprint np.linalg.norm(y1 - y2)\r\n\r\nfig = plt.figure()\r\nplt.plot( x, y1, '-' )\r\nplt.plot( x, y2, '--' )\r\nplt.show()\r\n\r\n```"}}