{"group":{"id":1,"name":"Community","lockable":false,"created_at":"2012-01-18T18:02:15.000Z","updated_at":"2025-12-14T01:33:56.000Z","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":"2025-12-14T00:00:00.000Z","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":703,"title":"Usage of varargout","description":"This Challenge is to demonstrate usage of varargout.\r\n\r\nOutput a cell array using varargout of magic squares of size 1 thru n.\r\n\r\n*Input:* n, Number of magic squares. Squares are of size 1:n\r\n\r\n*Output:* m_out, a cell array of n magic arrays \r\n\r\nn=3\r\n\r\nm_out{1} = [1] , \r\n\r\nm_out{2)=[1 3;4 2];  \r\n\r\nm_out{3}=[8 1 6;3 5 7; 4 9 2]\r\n\r\n\r\nThis Challenge is based upon a varargout implementation in Alfonso Castanon's top entry in the Knot's Challenge, \u003chttp://www.mathworks.com/matlabcentral/contest/contests/38/submissions/69705 lasttry05\u003e \r\n\r\n","description_html":"\u003cp\u003eThis Challenge is to demonstrate usage of varargout.\u003c/p\u003e\u003cp\u003eOutput a cell array using varargout of magic squares of size 1 thru n.\u003c/p\u003e\u003cp\u003e\u003cb\u003eInput:\u003c/b\u003e n, Number of magic squares. Squares are of size 1:n\u003c/p\u003e\u003cp\u003e\u003cb\u003eOutput:\u003c/b\u003e m_out, a cell array of n magic arrays\u003c/p\u003e\u003cp\u003en=3\u003c/p\u003e\u003cp\u003em_out{1} = [1] ,\u003c/p\u003e\u003cp\u003em_out{2)=[1 3;4 2];\u003c/p\u003e\u003cp\u003em_out{3}=[8 1 6;3 5 7; 4 9 2]\u003c/p\u003e\u003cp\u003eThis Challenge is based upon a varargout implementation in Alfonso Castanon's top entry in the Knot's Challenge, \u003ca href=\"http://www.mathworks.com/matlabcentral/contest/contests/38/submissions/69705\"\u003elasttry05\u003c/a\u003e\u003c/p\u003e","function_template":"function varargout = use_varargout(n)\r\n  varargout{1}=1;\r\nend","test_suite":"%%\r\nn=5;\r\n[m_out{1:n}] = use_varargout(n)\r\n\r\nPass=true;\r\nfor i=1:n\r\n Pass=Pass \u0026\u0026 isequal(m_out{i},magic(i));\r\nend\r\n\r\nm_out{n}\r\n\r\nassert(isequal(Pass,1))\r\n\r\n%%\r\nn=7;\r\n[m_out{1:n}] = use_varargout(n)\r\n\r\nPass=true;\r\nfor i=1:n\r\n Pass=Pass \u0026\u0026 isequal(m_out{i},magic(i));\r\nend\r\n\r\nm_out{n}\r\n\r\nassert(isequal(Pass,1))\r\n\r\n","published":true,"deleted":false,"likes_count":4,"comments_count":0,"created_by":3097,"edited_by":null,"edited_at":null,"deleted_by":null,"deleted_at":null,"solvers_count":76,"test_suite_updated_at":null,"rescore_all_solutions":false,"group_id":1,"created_at":"2012-05-20T05:58:03.000Z","updated_at":"2026-02-20T14:22:30.000Z","published_at":"2012-11-09T06:37:46.000Z","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\u003eThis Challenge is to demonstrate usage of varargout.\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\u003eOutput a cell array using varargout of magic squares of size 1 thru n.\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:rPr\u003e\u003cw:b/\u003e\u003c/w:rPr\u003e\u003cw:t\u003eInput:\u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:t\u003e n, Number of magic squares. Squares are of size 1:n\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:rPr\u003e\u003cw:b/\u003e\u003c/w:rPr\u003e\u003cw:t\u003eOutput:\u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:t\u003e m_out, a cell array of n magic arrays\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\u003en=3\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\u003em_out{1} = [1] ,\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\u003em_out{2)=[1 3;4 2];\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\u003em_out{3}=[8 1 6;3 5 7; 4 9 2]\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\u003eThis Challenge is based upon a varargout implementation in Alfonso Castanon's top entry in the Knot's Challenge,\u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:t\u003e \u003c/w:t\u003e\u003c/w:r\u003e\u003cw:hyperlink w:docLocation=\\\"http://www.mathworks.com/matlabcentral/contest/contests/38/submissions/69705\\\"\u003e\u003cw:r\u003e\u003cw:t\u003elasttry05\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:hyperlink\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":214,"title":"Filter values in a vector","description":"Cody often benefits from a functional style of programming. For example, your score is often better when you compose multiple functions instead of using intermediate variables. This problem involves creating a function to expand the repertoire of \"functional functions.\"\r\n\r\nFor this problem, write a filter function that applies a \"predicate\" function to a numeric, character, or cell vector and returns the elements for which the predicate returns true. Here are few examples:\r\n\r\n  filterfun(@isprime, 1:10)                     ==\u003e [2 3 5 7]\r\n  filterfun(@(c)c~='a', 'kayak radar')          ==\u003e 'kyk rdr'\r\n  filterfun(@(x)~isempty(x), {[]; 1; 'a'; []; {}}') ==\u003e {1; 'a'}\r\n\r\nNotes: If the vector |v| is a cell, you should apply the predicate to |v{i}| not |v(i)|. Also, |filterfun| should preserve the singleton dimension of the vector, i.e. if the input vector is a column vector the output should be a column vector.","description_html":"\u003cp\u003eCody often benefits from a functional style of programming. For example, your score is often better when you compose multiple functions instead of using intermediate variables. This problem involves creating a function to expand the repertoire of \"functional functions.\"\u003c/p\u003e\u003cp\u003eFor this problem, write a filter function that applies a \"predicate\" function to a numeric, character, or cell vector and returns the elements for which the predicate returns true. Here are few examples:\u003c/p\u003e\u003cpre class=\"language-matlab\"\u003efilterfun(@isprime, 1:10)                     ==\u003e [2 3 5 7]\r\nfilterfun(@(c)c~='a', 'kayak radar')          ==\u003e 'kyk rdr'\r\nfilterfun(@(x)~isempty(x), {[]; 1; 'a'; []; {}}') ==\u003e {1; 'a'}\r\n\u003c/pre\u003e\u003cp\u003eNotes: If the vector \u003ctt\u003ev\u003c/tt\u003e is a cell, you should apply the predicate to \u003ctt\u003ev{i}\u003c/tt\u003e not \u003ctt\u003ev(i)\u003c/tt\u003e. Also, \u003ctt\u003efilterfun\u003c/tt\u003e should preserve the singleton dimension of the vector, i.e. if the input vector is a column vector the output should be a column vector.\u003c/p\u003e","function_template":"function y = filterfun(fh, x)\r\n  y = x;\r\nend","test_suite":"%%\r\nx = (1:20)';\r\nfh = @(xi) mod(xi, 2) == 0;\r\ny_correct = (2:2:20)';\r\nassert(isequal(filterfun(fh, x), y_correct));\r\n\r\n%%\r\nx = 'Aa is lava.';\r\nfh = @(c) lower(c) == 'a';\r\ny_correct = 'Aaaa';\r\nassert(isequal(filterfun(fh, x), y_correct));\r\n\r\n%%\r\nx = {[]; 1; [1;2]; [2 3 4]; ones(1,1,3)};\r\nfh = @isrow;\r\ny_correct = {1; [2 3 4]};\r\nassert(isequal(filterfun(fh, x), y_correct));","published":true,"deleted":false,"likes_count":0,"comments_count":1,"created_by":321,"edited_by":null,"edited_at":null,"deleted_by":null,"deleted_at":null,"solvers_count":73,"test_suite_updated_at":"2012-02-01T15:44:58.000Z","rescore_all_solutions":false,"group_id":1,"created_at":"2012-02-01T15:44:58.000Z","updated_at":"2025-01-24T23:52:56.000Z","published_at":"2012-02-01T15:45:03.000Z","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\u003eCody often benefits from a functional style of programming. For example, your score is often better when you compose multiple functions instead of using intermediate variables. This problem involves creating a function to expand the repertoire of \\\"functional functions.\\\"\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 this problem, write a filter function that applies a \\\"predicate\\\" function to a numeric, character, or cell vector and returns the elements for which the predicate returns true. Here are few examples:\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[filterfun(@isprime, 1:10)                     ==\u003e [2 3 5 7]\\nfilterfun(@(c)c~='a', 'kayak radar')          ==\u003e 'kyk rdr'\\nfilterfun(@(x)~isempty(x), {[]; 1; 'a'; []; {}}') ==\u003e {1; 'a'}]]\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\u003eNotes: If the vector\u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:t\u003e \u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:rPr\u003e\u003cw:rFonts w:cs=\\\"monospace\\\"/\u003e\u003c/w:rPr\u003e\u003cw:t\u003ev\u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:t\u003e is a cell, you should apply the predicate to\u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:t\u003e \u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:rPr\u003e\u003cw:rFonts w:cs=\\\"monospace\\\"/\u003e\u003c/w:rPr\u003e\u003cw:t\u003ev{i}\u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:t\u003e not\u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:t\u003e \u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:rPr\u003e\u003cw:rFonts w:cs=\\\"monospace\\\"/\u003e\u003c/w:rPr\u003e\u003cw:t\u003ev(i)\u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:t\u003e. Also,\u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:t\u003e \u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:rPr\u003e\u003cw:rFonts w:cs=\\\"monospace\\\"/\u003e\u003c/w:rPr\u003e\u003cw:t\u003efilterfun\u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:t\u003e should preserve the singleton dimension of the vector, i.e. if the input vector is a column vector the output should be a column vector.\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":3095,"title":" Return fibonacci sequence do not use loop and condition version 2","description":"Calculate the nth Fibonacci number,return sequence\r\n\r\nGiven n, return f where f = fib(n) and f(1) = 1, f(2) = 1, f(3) = 2, ...\r\n\r\nExamples:\r\n\r\n Input  n = 2 : 5\r\n Output f is [1 2 3 5]\r\n Input  n = 7 : 10\r\n Output f is [13    21    34    55]\r\n\r\nbut, loop and conditional statement is forbidden","description_html":"\u003cp\u003eCalculate the nth Fibonacci number,return sequence\u003c/p\u003e\u003cp\u003eGiven n, return f where f = fib(n) and f(1) = 1, f(2) = 1, f(3) = 2, ...\u003c/p\u003e\u003cp\u003eExamples:\u003c/p\u003e\u003cpre\u003e Input  n = 2 : 5\r\n Output f is [1 2 3 5]\r\n Input  n = 7 : 10\r\n Output f is [13    21    34    55]\u003c/pre\u003e\u003cp\u003ebut, loop and conditional statement is forbidden\u003c/p\u003e","function_template":"function y = fib(x)\r\n  y = x;\r\nend","test_suite":"%%% Clean workspace\r\n% !/bin/cp fib.m safe\r\n% !/bin/rm *.*\r\n% !/bin/mv safe fib.m\r\n\r\n% Clean user's function from some known jailbreaking mechanisms\r\nfunctions={'!','feval','eval','str2func','str2num','regex','system','dos','unix','perl','assert','fopen','write','save','setenv','path','please','for','if','while','switch','round','roundn','fix','ceil','char','floor','\\.','^','power'};\r\nfid = fopen('fib.m');\r\n  st = char(fread(fid)');\r\n  for n = 1:numel(functions)\r\n    st = regexprep(st, functions{n}, 'error(''No fancy functions!''); %','ignorecase');\r\n  end\r\n  st = regexprep(st, 'function', 'error(''No fancy functions!''); %','ignorecase',2);\r\nfclose(fid);\r\nfid = fopen('fib.m' , 'w');\r\n  fwrite(fid,st);\r\nfclose(fid);\r\n\r\n%%\r\nn = 1:5;\r\nf = [1     1     2     3     5];\r\nassert(isequal(fib(n),f))\r\n\r\n%%\r\nn = 7 : 10;\r\nf = [13    21    34    55];\r\nassert(isequal(fib(n),f))\r\n\r\n%%\r\n\r\nn = 20 : 22;\r\nf = [ 6765       10946       17711];\r\nassert(isequal(fib(n),f))","published":true,"deleted":false,"likes_count":0,"comments_count":21,"created_by":3668,"edited_by":null,"edited_at":null,"deleted_by":null,"deleted_at":null,"solvers_count":64,"test_suite_updated_at":"2015-03-19T15:13:29.000Z","rescore_all_solutions":false,"group_id":30,"created_at":"2015-03-19T14:56:25.000Z","updated_at":"2026-03-16T14:37:24.000Z","published_at":"2015-03-19T14:56:25.000Z","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\u003eCalculate the nth Fibonacci number,return sequence\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\u003eGiven n, return f where f = fib(n) and f(1) = 1, f(2) = 1, f(3) = 2, ...\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\u003eExamples:\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[ Input  n = 2 : 5\\n Output f is [1 2 3 5]\\n Input  n = 7 : 10\\n Output f is [13    21    34    55]]]\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\u003ebut, loop and conditional statement is forbidden\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":{"errors":[],"problems":[{"id":703,"title":"Usage of varargout","description":"This Challenge is to demonstrate usage of varargout.\r\n\r\nOutput a cell array using varargout of magic squares of size 1 thru n.\r\n\r\n*Input:* n, Number of magic squares. Squares are of size 1:n\r\n\r\n*Output:* m_out, a cell array of n magic arrays \r\n\r\nn=3\r\n\r\nm_out{1} = [1] , \r\n\r\nm_out{2)=[1 3;4 2];  \r\n\r\nm_out{3}=[8 1 6;3 5 7; 4 9 2]\r\n\r\n\r\nThis Challenge is based upon a varargout implementation in Alfonso Castanon's top entry in the Knot's Challenge, \u003chttp://www.mathworks.com/matlabcentral/contest/contests/38/submissions/69705 lasttry05\u003e \r\n\r\n","description_html":"\u003cp\u003eThis Challenge is to demonstrate usage of varargout.\u003c/p\u003e\u003cp\u003eOutput a cell array using varargout of magic squares of size 1 thru n.\u003c/p\u003e\u003cp\u003e\u003cb\u003eInput:\u003c/b\u003e n, Number of magic squares. Squares are of size 1:n\u003c/p\u003e\u003cp\u003e\u003cb\u003eOutput:\u003c/b\u003e m_out, a cell array of n magic arrays\u003c/p\u003e\u003cp\u003en=3\u003c/p\u003e\u003cp\u003em_out{1} = [1] ,\u003c/p\u003e\u003cp\u003em_out{2)=[1 3;4 2];\u003c/p\u003e\u003cp\u003em_out{3}=[8 1 6;3 5 7; 4 9 2]\u003c/p\u003e\u003cp\u003eThis Challenge is based upon a varargout implementation in Alfonso Castanon's top entry in the Knot's Challenge, \u003ca href=\"http://www.mathworks.com/matlabcentral/contest/contests/38/submissions/69705\"\u003elasttry05\u003c/a\u003e\u003c/p\u003e","function_template":"function varargout = use_varargout(n)\r\n  varargout{1}=1;\r\nend","test_suite":"%%\r\nn=5;\r\n[m_out{1:n}] = use_varargout(n)\r\n\r\nPass=true;\r\nfor i=1:n\r\n Pass=Pass \u0026\u0026 isequal(m_out{i},magic(i));\r\nend\r\n\r\nm_out{n}\r\n\r\nassert(isequal(Pass,1))\r\n\r\n%%\r\nn=7;\r\n[m_out{1:n}] = use_varargout(n)\r\n\r\nPass=true;\r\nfor i=1:n\r\n Pass=Pass \u0026\u0026 isequal(m_out{i},magic(i));\r\nend\r\n\r\nm_out{n}\r\n\r\nassert(isequal(Pass,1))\r\n\r\n","published":true,"deleted":false,"likes_count":4,"comments_count":0,"created_by":3097,"edited_by":null,"edited_at":null,"deleted_by":null,"deleted_at":null,"solvers_count":76,"test_suite_updated_at":null,"rescore_all_solutions":false,"group_id":1,"created_at":"2012-05-20T05:58:03.000Z","updated_at":"2026-02-20T14:22:30.000Z","published_at":"2012-11-09T06:37:46.000Z","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\u003eThis Challenge is to demonstrate usage of varargout.\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\u003eOutput a cell array using varargout of magic squares of size 1 thru n.\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:rPr\u003e\u003cw:b/\u003e\u003c/w:rPr\u003e\u003cw:t\u003eInput:\u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:t\u003e n, Number of magic squares. Squares are of size 1:n\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:rPr\u003e\u003cw:b/\u003e\u003c/w:rPr\u003e\u003cw:t\u003eOutput:\u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:t\u003e m_out, a cell array of n magic arrays\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\u003en=3\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\u003em_out{1} = [1] ,\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\u003em_out{2)=[1 3;4 2];\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\u003em_out{3}=[8 1 6;3 5 7; 4 9 2]\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\u003eThis Challenge is based upon a varargout implementation in Alfonso Castanon's top entry in the Knot's Challenge,\u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:t\u003e \u003c/w:t\u003e\u003c/w:r\u003e\u003cw:hyperlink w:docLocation=\\\"http://www.mathworks.com/matlabcentral/contest/contests/38/submissions/69705\\\"\u003e\u003cw:r\u003e\u003cw:t\u003elasttry05\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:hyperlink\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":214,"title":"Filter values in a vector","description":"Cody often benefits from a functional style of programming. For example, your score is often better when you compose multiple functions instead of using intermediate variables. This problem involves creating a function to expand the repertoire of \"functional functions.\"\r\n\r\nFor this problem, write a filter function that applies a \"predicate\" function to a numeric, character, or cell vector and returns the elements for which the predicate returns true. Here are few examples:\r\n\r\n  filterfun(@isprime, 1:10)                     ==\u003e [2 3 5 7]\r\n  filterfun(@(c)c~='a', 'kayak radar')          ==\u003e 'kyk rdr'\r\n  filterfun(@(x)~isempty(x), {[]; 1; 'a'; []; {}}') ==\u003e {1; 'a'}\r\n\r\nNotes: If the vector |v| is a cell, you should apply the predicate to |v{i}| not |v(i)|. Also, |filterfun| should preserve the singleton dimension of the vector, i.e. if the input vector is a column vector the output should be a column vector.","description_html":"\u003cp\u003eCody often benefits from a functional style of programming. For example, your score is often better when you compose multiple functions instead of using intermediate variables. This problem involves creating a function to expand the repertoire of \"functional functions.\"\u003c/p\u003e\u003cp\u003eFor this problem, write a filter function that applies a \"predicate\" function to a numeric, character, or cell vector and returns the elements for which the predicate returns true. Here are few examples:\u003c/p\u003e\u003cpre class=\"language-matlab\"\u003efilterfun(@isprime, 1:10)                     ==\u003e [2 3 5 7]\r\nfilterfun(@(c)c~='a', 'kayak radar')          ==\u003e 'kyk rdr'\r\nfilterfun(@(x)~isempty(x), {[]; 1; 'a'; []; {}}') ==\u003e {1; 'a'}\r\n\u003c/pre\u003e\u003cp\u003eNotes: If the vector \u003ctt\u003ev\u003c/tt\u003e is a cell, you should apply the predicate to \u003ctt\u003ev{i}\u003c/tt\u003e not \u003ctt\u003ev(i)\u003c/tt\u003e. Also, \u003ctt\u003efilterfun\u003c/tt\u003e should preserve the singleton dimension of the vector, i.e. if the input vector is a column vector the output should be a column vector.\u003c/p\u003e","function_template":"function y = filterfun(fh, x)\r\n  y = x;\r\nend","test_suite":"%%\r\nx = (1:20)';\r\nfh = @(xi) mod(xi, 2) == 0;\r\ny_correct = (2:2:20)';\r\nassert(isequal(filterfun(fh, x), y_correct));\r\n\r\n%%\r\nx = 'Aa is lava.';\r\nfh = @(c) lower(c) == 'a';\r\ny_correct = 'Aaaa';\r\nassert(isequal(filterfun(fh, x), y_correct));\r\n\r\n%%\r\nx = {[]; 1; [1;2]; [2 3 4]; ones(1,1,3)};\r\nfh = @isrow;\r\ny_correct = {1; [2 3 4]};\r\nassert(isequal(filterfun(fh, x), y_correct));","published":true,"deleted":false,"likes_count":0,"comments_count":1,"created_by":321,"edited_by":null,"edited_at":null,"deleted_by":null,"deleted_at":null,"solvers_count":73,"test_suite_updated_at":"2012-02-01T15:44:58.000Z","rescore_all_solutions":false,"group_id":1,"created_at":"2012-02-01T15:44:58.000Z","updated_at":"2025-01-24T23:52:56.000Z","published_at":"2012-02-01T15:45:03.000Z","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\u003eCody often benefits from a functional style of programming. For example, your score is often better when you compose multiple functions instead of using intermediate variables. This problem involves creating a function to expand the repertoire of \\\"functional functions.\\\"\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 this problem, write a filter function that applies a \\\"predicate\\\" function to a numeric, character, or cell vector and returns the elements for which the predicate returns true. Here are few examples:\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[filterfun(@isprime, 1:10)                     ==\u003e [2 3 5 7]\\nfilterfun(@(c)c~='a', 'kayak radar')          ==\u003e 'kyk rdr'\\nfilterfun(@(x)~isempty(x), {[]; 1; 'a'; []; {}}') ==\u003e {1; 'a'}]]\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\u003eNotes: If the vector\u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:t\u003e \u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:rPr\u003e\u003cw:rFonts w:cs=\\\"monospace\\\"/\u003e\u003c/w:rPr\u003e\u003cw:t\u003ev\u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:t\u003e is a cell, you should apply the predicate to\u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:t\u003e \u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:rPr\u003e\u003cw:rFonts w:cs=\\\"monospace\\\"/\u003e\u003c/w:rPr\u003e\u003cw:t\u003ev{i}\u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:t\u003e not\u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:t\u003e \u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:rPr\u003e\u003cw:rFonts w:cs=\\\"monospace\\\"/\u003e\u003c/w:rPr\u003e\u003cw:t\u003ev(i)\u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:t\u003e. Also,\u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:t\u003e \u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:rPr\u003e\u003cw:rFonts w:cs=\\\"monospace\\\"/\u003e\u003c/w:rPr\u003e\u003cw:t\u003efilterfun\u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:t\u003e should preserve the singleton dimension of the vector, i.e. if the input vector is a column vector the output should be a column vector.\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 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x;\r\nend","test_suite":"%%% Clean workspace\r\n% !/bin/cp fib.m safe\r\n% !/bin/rm *.*\r\n% !/bin/mv safe fib.m\r\n\r\n% Clean user's function from some known jailbreaking mechanisms\r\nfunctions={'!','feval','eval','str2func','str2num','regex','system','dos','unix','perl','assert','fopen','write','save','setenv','path','please','for','if','while','switch','round','roundn','fix','ceil','char','floor','\\.','^','power'};\r\nfid = fopen('fib.m');\r\n  st = char(fread(fid)');\r\n  for n = 1:numel(functions)\r\n    st = regexprep(st, functions{n}, 'error(''No fancy functions!''); %','ignorecase');\r\n  end\r\n  st = regexprep(st, 'function', 'error(''No fancy functions!''); %','ignorecase',2);\r\nfclose(fid);\r\nfid = fopen('fib.m' , 'w');\r\n  fwrite(fid,st);\r\nfclose(fid);\r\n\r\n%%\r\nn = 1:5;\r\nf = [1     1     2     3     5];\r\nassert(isequal(fib(n),f))\r\n\r\n%%\r\nn = 7 : 10;\r\nf = [13    21    34    55];\r\nassert(isequal(fib(n),f))\r\n\r\n%%\r\n\r\nn = 20 : 22;\r\nf = [ 6765       10946       17711];\r\nassert(isequal(fib(n),f))","published":true,"deleted":false,"likes_count":0,"comments_count":21,"created_by":3668,"edited_by":null,"edited_at":null,"deleted_by":null,"deleted_at":null,"solvers_count":64,"test_suite_updated_at":"2015-03-19T15:13:29.000Z","rescore_all_solutions":false,"group_id":30,"created_at":"2015-03-19T14:56:25.000Z","updated_at":"2026-03-16T14:37:24.000Z","published_at":"2015-03-19T14:56:25.000Z","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 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