{"group":{"id":1,"name":"Community","lockable":false,"created_at":"2012-01-18T18:02:15.000Z","updated_at":"2026-05-26T00:16:20.000Z","description":"Problems submitted by members of the MATLAB Central community.","is_default":true,"created_by":161519,"badge_id":null,"featured":false,"trending":false,"solution_count_in_trending_period":0,"trending_last_calculated":"2026-05-26T00:00:00.000Z","image_id":null,"published":true,"community_created":false,"status_id":2,"is_default_group_for_player":false,"deleted_by":null,"deleted_at":null,"restored_by":null,"restored_at":null,"description_opc":null,"description_html":null,"published_at":null},"problems":[{"id":44613,"title":"Find NaNs in the matrix","description":"Return 1s wherever there is a NaN in the input matrix","description_html":"\u003cp\u003eReturn 1s wherever there is a NaN in the input matrix\u003c/p\u003e","function_template":"function y = return_nans(x)\r\n  \r\nend","test_suite":"%%\r\nx = 0./[6 4 0 3 -9];\r\ny_correct = [0   0   1   0   0];\r\nassert(isequal(return_nans(x),y_correct))\r\n\r\n%%\r\nx = [1 1 NaN NaN];\r\ny_correct = [0 0 1 1];\r\nassert(isequal(return_nans(x),y_correct))\r\n\r\n%%\r\nx =[1 1 NaN NaN; 5,2,3,NaN];\r\ny_correct = [0 0 1 1; 0 0 0 1];\r\nassert(isequal(return_nans(x),y_correct))\r\n","published":true,"deleted":false,"likes_count":0,"comments_count":0,"created_by":171559,"edited_by":null,"edited_at":null,"deleted_by":null,"deleted_at":null,"solvers_count":88,"test_suite_updated_at":null,"rescore_all_solutions":false,"group_id":1,"created_at":"2018-04-17T05:48:44.000Z","updated_at":"2026-05-29T04:26:52.000Z","published_at":"2018-04-17T05:48:44.000Z","restored_at":null,"restored_by":null,"spam":false,"simulink":false,"admin_reviewed":false,"description_opc":"{\"relationships\":[{\"relationshipType\":\"http://schemas.mathworks.com/matlab/code/2013/relationships/document\",\"relationshipId\":\"rId1\",\"target\":\"/matlab/document.xml\"},{\"relationshipType\":\"http://schemas.mathworks.com/matlab/code/2013/relationships/output\",\"relationshipId\":\"rId2\",\"target\":\"/matlab/output.xml\"}],\"parts\":[{\"partUri\":\"/matlab/document.xml\",\"relationship\":[],\"contentType\":\"application/vnd.mathworks.matlab.code.document+xml\",\"content\":\"\u003c?xml version=\\\"1.0\\\" encoding=\\\"UTF-8\\\"?\u003e\u003cw:document xmlns:w=\\\"http://schemas.openxmlformats.org/wordprocessingml/2006/main\\\"\u003e\u003cw:body\u003e\u003cw:p\u003e\u003cw:pPr\u003e\u003cw:pStyle w:val=\\\"text\\\"/\u003e\u003c/w:pPr\u003e\u003cw:r\u003e\u003cw:t\u003eReturn 1s wherever there is a NaN in the input matrix\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:p\u003e\u003c/w:body\u003e\u003c/w:document\u003e\"},{\"partUri\":\"/matlab/output.xml\",\"contentType\":\"text/xml\",\"content\":\"\u003c?xml version=\\\"1.0\\\" encoding=\\\"UTF-8\\\" standalone=\\\"no\\\" ?\u003e\u003cembeddedOutputs\u003e\u003cmetaData\u003e\u003cevaluationState\u003emanual\u003c/evaluationState\u003e\u003clayoutState\u003ecode\u003c/layoutState\u003e\u003coutputStatus\u003eready\u003c/outputStatus\u003e\u003c/metaData\u003e\u003coutputArray type=\\\"array\\\"/\u003e\u003cregionArray type=\\\"array\\\"/\u003e\u003c/embeddedOutputs\u003e\"}]}"},{"id":694,"title":"Remove NaNs and numbers adjacent to NaNs","description":"The aim is to remove the elements before and after NaN occurrences inside a vector.\r\n\r\nFor example:\r\n\r\n x = [6 10 5 8 9 NaN 23 10 7 3 21 43 NaN 4 6 7 8]\r\n\r\nThe output y will be:\r\n\r\n y = [6 10 5 8 10 7 3 21 6 7 8]\r\n\r\nIf NaNs occur at the beginning or end then first two or last two values are removed.\r\n\r\n x=[NaN 1 2 3]  yields [2 3]\r\n\r\nNaN values will exist in every case.\r\nNo case is an empty set.","description_html":"\u003cp\u003eThe aim is to remove the elements before and after NaN occurrences inside a vector.\u003c/p\u003e\u003cp\u003eFor example:\u003c/p\u003e\u003cpre\u003e x = [6 10 5 8 9 NaN 23 10 7 3 21 43 NaN 4 6 7 8]\u003c/pre\u003e\u003cp\u003eThe output y will be:\u003c/p\u003e\u003cpre\u003e y = [6 10 5 8 10 7 3 21 6 7 8]\u003c/pre\u003e\u003cp\u003eIf NaNs occur at the beginning or end then first two or last two values are removed.\u003c/p\u003e\u003cpre\u003e x=[NaN 1 2 3]  yields [2 3]\u003c/pre\u003e\u003cp\u003eNaN values will exist in every case.\r\nNo case is an empty set.\u003c/p\u003e","function_template":"function y = NaN_window_delete(x)\r\n  y=x;\r\nend","test_suite":"%% \r\nx=[1 2 3 NaN 4 5 6];\r\ny_correct=[1 2 5 6];\r\nassert(isequal(NaN_window_delete(x),y_correct))\r\n%% \r\nx=[10 20 3 NaN 4 50 NaN 6];\r\ny_correct=[10 20];\r\nassert(isequal(NaN_window_delete(x),y_correct))\r\n%% \r\nx=[NaN 20 3 5 4 50 55 NaN];\r\ny_correct=[3 5 4 50];\r\nassert(isequal(NaN_window_delete(x),y_correct))\r\n%% \r\nx=[10 20 3 5 NaN 4 50 55 NaN 60 80 90 NaN 100 110 ];\r\ny_correct=[10 20 3 50 80 110];\r\nassert(isequal(NaN_window_delete(x),y_correct))\r\n","published":true,"deleted":false,"likes_count":1,"comments_count":0,"created_by":3097,"edited_by":null,"edited_at":null,"deleted_by":null,"deleted_at":null,"solvers_count":80,"test_suite_updated_at":"2012-05-16T21:35:19.000Z","rescore_all_solutions":false,"group_id":1,"created_at":"2012-05-16T21:24:52.000Z","updated_at":"2026-03-10T15:29:04.000Z","published_at":"2012-05-16T21:35:19.000Z","restored_at":null,"restored_by":null,"spam":false,"simulink":false,"admin_reviewed":false,"description_opc":"{\"relationships\":[{\"relationshipType\":\"http://schemas.mathworks.com/matlab/code/2013/relationships/document\",\"targetMode\":\"\",\"relationshipId\":\"rId1\",\"target\":\"/matlab/document.xml\"},{\"relationshipType\":\"http://schemas.mathworks.com/matlab/code/2013/relationships/output\",\"targetMode\":\"\",\"relationshipId\":\"rId2\",\"target\":\"/matlab/output.xml\"}],\"parts\":[{\"partUri\":\"/matlab/document.xml\",\"relationship\":[],\"contentType\":\"application/vnd.mathworks.matlab.code.document+xml\",\"content\":\"\u003c?xml version=\\\"1.0\\\" encoding=\\\"UTF-8\\\"?\u003e\\n\u003cw:document xmlns:w=\\\"http://schemas.openxmlformats.org/wordprocessingml/2006/main\\\"\u003e\u003cw:body\u003e\u003cw:p\u003e\u003cw:pPr\u003e\u003cw:pStyle w:val=\\\"text\\\"/\u003e\u003c/w:pPr\u003e\u003cw:r\u003e\u003cw:t\u003eThe aim is to remove the elements before and after NaN occurrences inside a vector.\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:p\u003e\u003cw:p\u003e\u003cw:pPr\u003e\u003cw:pStyle w:val=\\\"text\\\"/\u003e\u003c/w:pPr\u003e\u003cw:r\u003e\u003cw:t\u003eFor example:\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:p\u003e\u003cw:p\u003e\u003cw:pPr\u003e\u003cw:pStyle w:val=\\\"code\\\"/\u003e\u003c/w:pPr\u003e\u003cw:r\u003e\u003cw:t\u003e\u003c![CDATA[ x = [6 10 5 8 9 NaN 23 10 7 3 21 43 NaN 4 6 7 8]]]\u003e\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:p\u003e\u003cw:p\u003e\u003cw:pPr\u003e\u003cw:pStyle w:val=\\\"text\\\"/\u003e\u003c/w:pPr\u003e\u003cw:r\u003e\u003cw:t\u003eThe output y will be:\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:p\u003e\u003cw:p\u003e\u003cw:pPr\u003e\u003cw:pStyle w:val=\\\"code\\\"/\u003e\u003c/w:pPr\u003e\u003cw:r\u003e\u003cw:t\u003e\u003c![CDATA[ y = [6 10 5 8 10 7 3 21 6 7 8]]]\u003e\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:p\u003e\u003cw:p\u003e\u003cw:pPr\u003e\u003cw:pStyle w:val=\\\"text\\\"/\u003e\u003c/w:pPr\u003e\u003cw:r\u003e\u003cw:t\u003eIf NaNs occur at the beginning or end then first two or last two values are removed.\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:p\u003e\u003cw:p\u003e\u003cw:pPr\u003e\u003cw:pStyle w:val=\\\"code\\\"/\u003e\u003c/w:pPr\u003e\u003cw:r\u003e\u003cw:t\u003e\u003c![CDATA[ x=[NaN 1 2 3]  yields [2 3]]]\u003e\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:p\u003e\u003cw:p\u003e\u003cw:pPr\u003e\u003cw:pStyle w:val=\\\"text\\\"/\u003e\u003c/w:pPr\u003e\u003cw:r\u003e\u003cw:t\u003eNaN values will exist in every case. No case is an empty set.\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:p\u003e\u003c/w:body\u003e\u003c/w:document\u003e\"},{\"partUri\":\"/matlab/output.xml\",\"contentType\":\"text/xml\",\"content\":\"\u003c?xml version=\\\"1.0\\\" encoding=\\\"UTF-8\\\" standalone=\\\"no\\\" ?\u003e\u003cembeddedOutputs\u003e\u003cmetaData\u003e\u003cevaluationState\u003emanual\u003c/evaluationState\u003e\u003clayoutState\u003ecode\u003c/layoutState\u003e\u003coutputStatus\u003eready\u003c/outputStatus\u003e\u003c/metaData\u003e\u003coutputArray type=\\\"array\\\"/\u003e\u003cregionArray type=\\\"array\\\"/\u003e\u003c/embeddedOutputs\u003e\"}]}"}],"problem_search":{"problems":[{"id":44613,"title":"Find NaNs in the matrix","description":"Return 1s wherever there is a NaN in the input matrix","description_html":"\u003cp\u003eReturn 1s wherever there is a NaN in the input matrix\u003c/p\u003e","function_template":"function y = return_nans(x)\r\n  \r\nend","test_suite":"%%\r\nx = 0./[6 4 0 3 -9];\r\ny_correct = [0   0   1   0   0];\r\nassert(isequal(return_nans(x),y_correct))\r\n\r\n%%\r\nx = [1 1 NaN NaN];\r\ny_correct = [0 0 1 1];\r\nassert(isequal(return_nans(x),y_correct))\r\n\r\n%%\r\nx =[1 1 NaN NaN; 5,2,3,NaN];\r\ny_correct = [0 0 1 1; 0 0 0 1];\r\nassert(isequal(return_nans(x),y_correct))\r\n","published":true,"deleted":false,"likes_count":0,"comments_count":0,"created_by":171559,"edited_by":null,"edited_at":null,"deleted_by":null,"deleted_at":null,"solvers_count":88,"test_suite_updated_at":null,"rescore_all_solutions":false,"group_id":1,"created_at":"2018-04-17T05:48:44.000Z","updated_at":"2026-05-29T04:26:52.000Z","published_at":"2018-04-17T05:48:44.000Z","restored_at":null,"restored_by":null,"spam":false,"simulink":false,"admin_reviewed":false,"description_opc":"{\"relationships\":[{\"relationshipType\":\"http://schemas.mathworks.com/matlab/code/2013/relationships/document\",\"relationshipId\":\"rId1\",\"target\":\"/matlab/document.xml\"},{\"relationshipType\":\"http://schemas.mathworks.com/matlab/code/2013/relationships/output\",\"relationshipId\":\"rId2\",\"target\":\"/matlab/output.xml\"}],\"parts\":[{\"partUri\":\"/matlab/document.xml\",\"relationship\":[],\"contentType\":\"application/vnd.mathworks.matlab.code.document+xml\",\"content\":\"\u003c?xml version=\\\"1.0\\\" encoding=\\\"UTF-8\\\"?\u003e\u003cw:document xmlns:w=\\\"http://schemas.openxmlformats.org/wordprocessingml/2006/main\\\"\u003e\u003cw:body\u003e\u003cw:p\u003e\u003cw:pPr\u003e\u003cw:pStyle w:val=\\\"text\\\"/\u003e\u003c/w:pPr\u003e\u003cw:r\u003e\u003cw:t\u003eReturn 1s wherever there is a NaN in the input matrix\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:p\u003e\u003c/w:body\u003e\u003c/w:document\u003e\"},{\"partUri\":\"/matlab/output.xml\",\"contentType\":\"text/xml\",\"content\":\"\u003c?xml version=\\\"1.0\\\" encoding=\\\"UTF-8\\\" standalone=\\\"no\\\" ?\u003e\u003cembeddedOutputs\u003e\u003cmetaData\u003e\u003cevaluationState\u003emanual\u003c/evaluationState\u003e\u003clayoutState\u003ecode\u003c/layoutState\u003e\u003coutputStatus\u003eready\u003c/outputStatus\u003e\u003c/metaData\u003e\u003coutputArray type=\\\"array\\\"/\u003e\u003cregionArray type=\\\"array\\\"/\u003e\u003c/embeddedOutputs\u003e\"}]}"},{"id":694,"title":"Remove NaNs and numbers adjacent to NaNs","description":"The aim is to remove the elements before and after NaN occurrences inside a vector.\r\n\r\nFor example:\r\n\r\n x = [6 10 5 8 9 NaN 23 10 7 3 21 43 NaN 4 6 7 8]\r\n\r\nThe output y will be:\r\n\r\n y = [6 10 5 8 10 7 3 21 6 7 8]\r\n\r\nIf NaNs occur at the beginning or end then first two or last two values are removed.\r\n\r\n x=[NaN 1 2 3]  yields [2 3]\r\n\r\nNaN values will exist in every case.\r\nNo case is an empty set.","description_html":"\u003cp\u003eThe aim is to remove the elements before and after NaN occurrences inside a vector.\u003c/p\u003e\u003cp\u003eFor example:\u003c/p\u003e\u003cpre\u003e x = [6 10 5 8 9 NaN 23 10 7 3 21 43 NaN 4 6 7 8]\u003c/pre\u003e\u003cp\u003eThe output y will be:\u003c/p\u003e\u003cpre\u003e y = [6 10 5 8 10 7 3 21 6 7 8]\u003c/pre\u003e\u003cp\u003eIf NaNs occur at the beginning or end then first two or last two values are removed.\u003c/p\u003e\u003cpre\u003e x=[NaN 1 2 3]  yields [2 3]\u003c/pre\u003e\u003cp\u003eNaN values will exist in every case.\r\nNo case is an empty set.\u003c/p\u003e","function_template":"function y = NaN_window_delete(x)\r\n  y=x;\r\nend","test_suite":"%% \r\nx=[1 2 3 NaN 4 5 6];\r\ny_correct=[1 2 5 6];\r\nassert(isequal(NaN_window_delete(x),y_correct))\r\n%% \r\nx=[10 20 3 NaN 4 50 NaN 6];\r\ny_correct=[10 20];\r\nassert(isequal(NaN_window_delete(x),y_correct))\r\n%% \r\nx=[NaN 20 3 5 4 50 55 NaN];\r\ny_correct=[3 5 4 50];\r\nassert(isequal(NaN_window_delete(x),y_correct))\r\n%% \r\nx=[10 20 3 5 NaN 4 50 55 NaN 60 80 90 NaN 100 110 ];\r\ny_correct=[10 20 3 50 80 110];\r\nassert(isequal(NaN_window_delete(x),y_correct))\r\n","published":true,"deleted":false,"likes_count":1,"comments_count":0,"created_by":3097,"edited_by":null,"edited_at":null,"deleted_by":null,"deleted_at":null,"solvers_count":80,"test_suite_updated_at":"2012-05-16T21:35:19.000Z","rescore_all_solutions":false,"group_id":1,"created_at":"2012-05-16T21:24:52.000Z","updated_at":"2026-03-10T15:29:04.000Z","published_at":"2012-05-16T21:35:19.000Z","restored_at":null,"restored_by":null,"spam":false,"simulink":false,"admin_reviewed":false,"description_opc":"{\"relationships\":[{\"relationshipType\":\"http://schemas.mathworks.com/matlab/code/2013/relationships/document\",\"targetMode\":\"\",\"relationshipId\":\"rId1\",\"target\":\"/matlab/document.xml\"},{\"relationshipType\":\"http://schemas.mathworks.com/matlab/code/2013/relationships/output\",\"targetMode\":\"\",\"relationshipId\":\"rId2\",\"target\":\"/matlab/output.xml\"}],\"parts\":[{\"partUri\":\"/matlab/document.xml\",\"relationship\":[],\"contentType\":\"application/vnd.mathworks.matlab.code.document+xml\",\"content\":\"\u003c?xml version=\\\"1.0\\\" encoding=\\\"UTF-8\\\"?\u003e\\n\u003cw:document xmlns:w=\\\"http://schemas.openxmlformats.org/wordprocessingml/2006/main\\\"\u003e\u003cw:body\u003e\u003cw:p\u003e\u003cw:pPr\u003e\u003cw:pStyle w:val=\\\"text\\\"/\u003e\u003c/w:pPr\u003e\u003cw:r\u003e\u003cw:t\u003eThe aim is to remove the elements before and after NaN occurrences inside a vector.\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:p\u003e\u003cw:p\u003e\u003cw:pPr\u003e\u003cw:pStyle w:val=\\\"text\\\"/\u003e\u003c/w:pPr\u003e\u003cw:r\u003e\u003cw:t\u003eFor example:\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:p\u003e\u003cw:p\u003e\u003cw:pPr\u003e\u003cw:pStyle w:val=\\\"code\\\"/\u003e\u003c/w:pPr\u003e\u003cw:r\u003e\u003cw:t\u003e\u003c![CDATA[ x = [6 10 5 8 9 NaN 23 10 7 3 21 43 NaN 4 6 7 8]]]\u003e\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:p\u003e\u003cw:p\u003e\u003cw:pPr\u003e\u003cw:pStyle w:val=\\\"text\\\"/\u003e\u003c/w:pPr\u003e\u003cw:r\u003e\u003cw:t\u003eThe output y will be:\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:p\u003e\u003cw:p\u003e\u003cw:pPr\u003e\u003cw:pStyle w:val=\\\"code\\\"/\u003e\u003c/w:pPr\u003e\u003cw:r\u003e\u003cw:t\u003e\u003c![CDATA[ y = [6 10 5 8 10 7 3 21 6 7 8]]]\u003e\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:p\u003e\u003cw:p\u003e\u003cw:pPr\u003e\u003cw:pStyle w:val=\\\"text\\\"/\u003e\u003c/w:pPr\u003e\u003cw:r\u003e\u003cw:t\u003eIf NaNs occur at the beginning or end then first two or last two values are removed.\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:p\u003e\u003cw:p\u003e\u003cw:pPr\u003e\u003cw:pStyle w:val=\\\"code\\\"/\u003e\u003c/w:pPr\u003e\u003cw:r\u003e\u003cw:t\u003e\u003c![CDATA[ x=[NaN 1 2 3]  yields [2 3]]]\u003e\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:p\u003e\u003cw:p\u003e\u003cw:pPr\u003e\u003cw:pStyle w:val=\\\"text\\\"/\u003e\u003c/w:pPr\u003e\u003cw:r\u003e\u003cw:t\u003eNaN values will exist in every case. No case is an empty set.\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:p\u003e\u003c/w:body\u003e\u003c/w:document\u003e\"},{\"partUri\":\"/matlab/output.xml\",\"contentType\":\"text/xml\",\"content\":\"\u003c?xml version=\\\"1.0\\\" encoding=\\\"UTF-8\\\" standalone=\\\"no\\\" ?\u003e\u003cembeddedOutputs\u003e\u003cmetaData\u003e\u003cevaluationState\u003emanual\u003c/evaluationState\u003e\u003clayoutState\u003ecode\u003c/layoutState\u003e\u003coutputStatus\u003eready\u003c/outputStatus\u003e\u003c/metaData\u003e\u003coutputArray type=\\\"array\\\"/\u003e\u003cregionArray type=\\\"array\\\"/\u003e\u003c/embeddedOutputs\u003e\"}]}"}],"errors":[],"facets":[[],[{"value":"easy","count":2,"selected":false}]],"term":"tag:\"isnan\"","page":1,"per_page":50,"sort":"map(difficulty_value,0,0,999) asc"}}