{"action":"created","issue":{"url":"https://api.github.com/repos/ValeevGroup/tiledarray/issues/37","labels_url":"https://api.github.com/repos/ValeevGroup/tiledarray/issues/37/labels{/name}","comments_url":"https://api.github.com/repos/ValeevGroup/tiledarray/issues/37/comments","events_url":"https://api.github.com/repos/ValeevGroup/tiledarray/issues/37/events","html_url":"https://github.com/ValeevGroup/tiledarray/issues/37","id":112060511,"number":37,"title":"assignment etc to BlkTsrExpr","user":{"login":"shiozaki","id":1324578,"avatar_url":"https://avatars.githubusercontent.com/u/1324578?v=3","gravatar_id":"","url":"https://api.github.com/users/shiozaki","html_url":"https://github.com/shiozaki","followers_url":"https://api.github.com/users/shiozaki/followers","following_url":"https://api.github.com/users/shiozaki/following{/other_user}","gists_url":"https://api.github.com/users/shiozaki/gists{/gist_id}","starred_url":"https://api.github.com/users/shiozaki/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/shiozaki/subscriptions","organizations_url":"https://api.github.com/users/shiozaki/orgs","repos_url":"https://api.github.com/users/shiozaki/repos","events_url":"https://api.github.com/users/shiozaki/events{/privacy}","received_events_url":"https://api.github.com/users/shiozaki/received_events","type":"User","site_admin":false},"labels":[{"url":"https://api.github.com/repos/ValeevGroup/tiledarray/labels/enhancement","name":"enhancement","color":"84b6eb"}],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":15,"created_at":"2015-10-19T02:33:49Z","updated_at":"2015-10-22T15:49:38Z","closed_at":null,"body":"Because assignment, += and, -= are deleted, one cannot do this sort of operation.\r\n```\r\na(\"a2,c1,a4,c3\").block({2,0,2,0}, {4,1,4,1})\r\n= b(\"x1,a2,c1,a4\").block({1,2,0,2}, {2,4,1,4}) * c(\"c3,x1\").block({0,1}, {1,2});\r\n```\r\nThis use case is *very* common in MR theories because the target residual tensor has some super-structure, requiring us to use the block expressions for tensors on the left.\r\n\r\nPS: @evaleev  this is what I meant in the email."},"comment":{"url":"https://api.github.com/repos/ValeevGroup/tiledarray/issues/comments/150268440","html_url":"https://github.com/ValeevGroup/tiledarray/issues/37#issuecomment-150268440","issue_url":"https://api.github.com/repos/ValeevGroup/tiledarray/issues/37","id":150268440,"user":{"login":"shiozaki","id":1324578,"avatar_url":"https://avatars.githubusercontent.com/u/1324578?v=3","gravatar_id":"","url":"https://api.github.com/users/shiozaki","html_url":"https://github.com/shiozaki","followers_url":"https://api.github.com/users/shiozaki/followers","following_url":"https://api.github.com/users/shiozaki/following{/other_user}","gists_url":"https://api.github.com/users/shiozaki/gists{/gist_id}","starred_url":"https://api.github.com/users/shiozaki/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/shiozaki/subscriptions","organizations_url":"https://api.github.com/users/shiozaki/orgs","repos_url":"https://api.github.com/users/shiozaki/repos","events_url":"https://api.github.com/users/shiozaki/events{/privacy}","received_events_url":"https://api.github.com/users/shiozaki/received_events","type":"User","site_admin":false},"created_at":"2015-10-22T15:49:38Z","updated_at":"2015-10-22T15:49:38Z","body":"I am calling (ta0, ta1 and ta2 are my wrapper class objects)\r\n```\r\n(*ta0)(\"a2,c1,a4,c3\") += (*ta1)(\"x1,a2,c1,a4\") * (*ta2)(\"c3,x1\");\r\n```\r\nand the definition of the operator() of my class is\r\n```\r\nauto operator()(const std::string& vars) -> decltype(TiledArray::Array<DataType,N>::operator()(vars).block(std::array<size_t,N>(), std::array<size_t, N>()))\r\n```"}}