{"action":"opened","issue":{"url":"https://api.github.com/repos/e0404/matRad/issues/3","labels_url":"https://api.github.com/repos/e0404/matRad/issues/3/labels{/name}","comments_url":"https://api.github.com/repos/e0404/matRad/issues/3/comments","events_url":"https://api.github.com/repos/e0404/matRad/issues/3/events","html_url":"https://github.com/e0404/matRad/issues/3","id":55204970,"number":3,"title":"custom sparse matrix format","user":{"login":"markbangert","id":10157181,"avatar_url":"https://avatars.githubusercontent.com/u/10157181?v=3","gravatar_id":"","url":"https://api.github.com/users/markbangert","html_url":"https://github.com/markbangert","followers_url":"https://api.github.com/users/markbangert/followers","following_url":"https://api.github.com/users/markbangert/following{/other_user}","gists_url":"https://api.github.com/users/markbangert/gists{/gist_id}","starred_url":"https://api.github.com/users/markbangert/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/markbangert/subscriptions","organizations_url":"https://api.github.com/users/markbangert/orgs","repos_url":"https://api.github.com/users/markbangert/repos","events_url":"https://api.github.com/users/markbangert/events{/privacy}","received_events_url":"https://api.github.com/users/markbangert/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":0,"created_at":"2015-01-22T20:33:11Z","updated_at":"2015-01-22T20:33:11Z","closed_at":null,"body":"matlabs built-in sparse matrix format suffers from the following limitations\r\n*only double precision possible (memory issues)\r\n*uses int64 to store the index value which has a maximum value of\r\nintmax('int64')=9223372036854775807\r\nfor our purposes\r\nintmax('int32')=2147483647\r\nwould suffice\r\n* considering worst case optimization and biological optimization where we have to store multiple values per index a custum format might save even more memory!\r\n\r\nthe question is can we design a format the still allows for efficient dose calculation - and I am afraid the answer is no.... :("}}