{"action":"closed","issue":{"url":"https://api.github.com/repos/davidedc/Algebrite/issues/20","repository_url":"https://api.github.com/repos/davidedc/Algebrite","labels_url":"https://api.github.com/repos/davidedc/Algebrite/issues/20/labels{/name}","comments_url":"https://api.github.com/repos/davidedc/Algebrite/issues/20/comments","events_url":"https://api.github.com/repos/davidedc/Algebrite/issues/20/events","html_url":"https://github.com/davidedc/Algebrite/issues/20","id":160792595,"number":20,"title":"sum","user":{"login":"MayaKirillova","id":7105995,"avatar_url":"https://avatars.githubusercontent.com/u/7105995?v=3","gravatar_id":"","url":"https://api.github.com/users/MayaKirillova","html_url":"https://github.com/MayaKirillova","followers_url":"https://api.github.com/users/MayaKirillova/followers","following_url":"https://api.github.com/users/MayaKirillova/following{/other_user}","gists_url":"https://api.github.com/users/MayaKirillova/gists{/gist_id}","starred_url":"https://api.github.com/users/MayaKirillova/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/MayaKirillova/subscriptions","organizations_url":"https://api.github.com/users/MayaKirillova/orgs","repos_url":"https://api.github.com/users/MayaKirillova/repos","events_url":"https://api.github.com/users/MayaKirillova/events{/privacy}","received_events_url":"https://api.github.com/users/MayaKirillova/received_events","type":"User","site_admin":false},"labels":[],"state":"closed","locked":false,"assignee":null,"assignees":[],"milestone":null,"comments":1,"created_at":"2016-06-17T00:59:48Z","updated_at":"2016-08-28T11:13:20Z","closed_at":"2016-08-28T11:13:20Z","body":"The `sum` function is listed in the **Algebrite** [function reference](http://algebrite.org/reference.html#sum), but doesn't appear to have an implementation yet.\r\n\r\nThe function reference says:\r\n\r\n> **sum(i,j,k,f)**\r\n> \r\n> For i equals j through k evaluate f. Returns the sum of all f.\r\n\r\nBut when I execute the following code in nodejs\r\n\r\n```\r\nvar Algebrite = require('algebrite');\r\nAlgebrite.run('sum(n,1,6,x^n)');\r\n```\r\n\r\nI get the error message\r\n\r\n> 'Eval_sum is not defined'\r\n\r\nBy contrast, if I execute the same expression in **eigenmath**, I get the following results:\r\n\r\n```\r\n$ ./math\r\n> sum(n,1,6,x^n)\r\n 6    5    4    3    2\r\nx  + x  + x  + x  + x  + x\r\n```\r\n\r\nMy goal is to be able to evaluate even more complicated expressions such as\r\n\r\n```\r\nsum(k,2,12,coeff((sum(n,1,6,x^n))^2,x,k))\r\n```\r\n\r\nwhich should return 36.\r\n\r\nThanks!\r\n"}}
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