{"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":1898,"title":"Too Many Zeros, Dump Them!","description":"Sometimes when I create a matrix, I use this syntax:\r\n\r\n a = zeros(1000,1000);\r\n\r\nBut when the function ends, I find that I don't want all those zeros. Then I need another function to dump the extra zeros located to the south-east of the matrix.\r\n\r\nFor example:\r\n  \r\n a1 = [1 2 0;\r\n       0 3 0;\r\n       0 0 0];\r\n\r\nI want to get a new matrix ,that is:\r\n\r\n b1 = [1 2;\r\n       0 3];\r\n\r\nAnother example:\r\n\r\n a2 = [1 2 0 4 0;\r\n       2 3 0 5 0;\r\n       3 4 0 6 0;\r\n       1 0 0 0 0];\r\n\r\n b2 = [1 2 0 4;\r\n       2 3 0 5;\r\n       3 4 0 6;\r\n       1 0 0 0];\r\n\r\nGood Luck!\r\n","description_html":"\u003cp\u003eSometimes when I create a matrix, I use this syntax:\u003c/p\u003e\u003cpre\u003e a = zeros(1000,1000);\u003c/pre\u003e\u003cp\u003eBut when the function ends, I find that I don't want all those zeros. Then I need another function to dump the extra zeros located to the south-east of the matrix.\u003c/p\u003e\u003cp\u003eFor example:\u003c/p\u003e\u003cpre\u003e a1 = [1 2 0;\r\n       0 3 0;\r\n       0 0 0];\u003c/pre\u003e\u003cp\u003eI want to get a new matrix ,that is:\u003c/p\u003e\u003cpre\u003e b1 = [1 2;\r\n       0 3];\u003c/pre\u003e\u003cp\u003eAnother example:\u003c/p\u003e\u003cpre\u003e a2 = [1 2 0 4 0;\r\n       2 3 0 5 0;\r\n       3 4 0 6 0;\r\n       1 0 0 0 0];\u003c/pre\u003e\u003cpre\u003e b2 = [1 2 0 4;\r\n       2 3 0 5;\r\n       3 4 0 6;\r\n       1 0 0 0];\u003c/pre\u003e\u003cp\u003eGood Luck!\u003c/p\u003e","function_template":"function b = ZeroDumping(a)\r\nb=a;\r\nend","test_suite":"%%\r\nx = 0;\r\ny_correct = [];\r\nassert(isequal(ZeroDumping(x),y_correct))\r\n\r\n%%\r\nx = 1;\r\ny_correct = 1;\r\nassert(isequal(ZeroDumping(x),y_correct))\r\n\r\n%%\r\nx = [1 0];\r\ny_correct = 1;\r\nassert(isequal(ZeroDumping(x),y_correct))\r\n\r\n%%\r\nx = [1 0 1 0;\r\n     0 0 1 0];\r\ny_correct = [1 0 1\r\n             0 0 1];\r\nassert(isequal(ZeroDumping(x),y_correct));\r\n\r\n%%\r\nx=[1,0,  -3, 1i,0;\r\n   2,0.3,2i, 0, 0;\r\n   0,0,   0, inf, 0;\r\n   0,0,   0, 0, 1];\r\ny_correct =x;% x(4,5) is useful, I don't want to dump it.\r\nassert(isequal(ZeroDumping(x),y_correct));\r\n\r\n%%\r\nx =[0\t0\t0\t0\t0\r\n0\t0\t0\t0\t0\r\n0\t0\t0\t0\t0\r\n0\t0\t0\t0\t0\r\n0\t0\t0\t0\teps];\r\ny_correct =x;\r\nassert(isequal(ZeroDumping(x),y_correct));\r\n\r\n%%\r\nx =[1\t1\t0\t0\t0\r\n    1\t0\t0\t0\t0\r\n    0\t0\t0\t3\t0\r\n    0\t0\t0\t0\t0\r\n    0\t0\t0\t0\t0];\r\ny_correct =[1\t1\t0\t0\r\n            1\t0\t0\t0\r\n            0\t0\t0\t3];\r\nassert(isequal(ZeroDumping(x),y_correct));\r\n\r\n%%\r\nx =[1\t1\t0\t0\t0\r\n    1\t0\t0\t0\t0\r\n    0\t0\t0\t3\t0\r\n    0\t0\t0\t0\tinf\r\n    0\t0\t0\t0\t0];\r\ny_correct =[1\t1\t0\t0\t0\r\n\t    1\t0\t0\t0\t0\r\n\t    0\t0\t0\t3\t0\r\n\t    0\t0\t0\t0\tinf];\r\nassert(isequal(ZeroDumping(x),y_correct));\r\n","published":true,"deleted":false,"likes_count":5,"comments_count":0,"created_by":7365,"edited_by":null,"edited_at":null,"deleted_by":null,"deleted_at":null,"solvers_count":283,"test_suite_updated_at":"2013-09-27T16:23:12.000Z","rescore_all_solutions":false,"group_id":23,"created_at":"2013-09-27T11:48:40.000Z","updated_at":"2026-05-04T03:14:52.000Z","published_at":"2013-09-27T12:56:24.000Z","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\u003eSometimes when I create a matrix, I use this syntax:\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[ a = zeros(1000,1000);]]\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 when the function ends, I find that I don't want all those zeros. Then I need another function to dump the extra zeros located to the south-east of the matrix.\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[ a1 = [1 2 0;\\n       0 3 0;\\n       0 0 0];]]\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\u003eI want to get a new matrix ,that is:\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[ b1 = [1 2;\\n       0 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\u003eAnother 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[ a2 = [1 2 0 4 0;\\n       2 3 0 5 0;\\n       3 4 0 6 0;\\n       1 0 0 0 0];\\n\\n b2 = [1 2 0 4;\\n       2 3 0 5;\\n       3 4 0 6;\\n       1 0 0 0];]]\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\u003eGood Luck!\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":1898,"title":"Too Many Zeros, Dump Them!","description":"Sometimes when I create a matrix, I use this syntax:\r\n\r\n a = zeros(1000,1000);\r\n\r\nBut when the function ends, I find that I don't want all those zeros. Then I need another function to dump the extra zeros located to the south-east of the matrix.\r\n\r\nFor example:\r\n  \r\n a1 = [1 2 0;\r\n       0 3 0;\r\n       0 0 0];\r\n\r\nI want to get a new matrix ,that is:\r\n\r\n b1 = [1 2;\r\n       0 3];\r\n\r\nAnother example:\r\n\r\n a2 = [1 2 0 4 0;\r\n       2 3 0 5 0;\r\n       3 4 0 6 0;\r\n       1 0 0 0 0];\r\n\r\n b2 = [1 2 0 4;\r\n       2 3 0 5;\r\n       3 4 0 6;\r\n       1 0 0 0];\r\n\r\nGood Luck!\r\n","description_html":"\u003cp\u003eSometimes when I create a matrix, I use this syntax:\u003c/p\u003e\u003cpre\u003e a = zeros(1000,1000);\u003c/pre\u003e\u003cp\u003eBut when the function ends, I find that I don't want all those zeros. Then I need another function to dump the extra zeros located to the south-east of the matrix.\u003c/p\u003e\u003cp\u003eFor example:\u003c/p\u003e\u003cpre\u003e a1 = [1 2 0;\r\n       0 3 0;\r\n       0 0 0];\u003c/pre\u003e\u003cp\u003eI want to get a new matrix ,that is:\u003c/p\u003e\u003cpre\u003e b1 = [1 2;\r\n       0 3];\u003c/pre\u003e\u003cp\u003eAnother example:\u003c/p\u003e\u003cpre\u003e a2 = [1 2 0 4 0;\r\n       2 3 0 5 0;\r\n       3 4 0 6 0;\r\n       1 0 0 0 0];\u003c/pre\u003e\u003cpre\u003e b2 = [1 2 0 4;\r\n       2 3 0 5;\r\n       3 4 0 6;\r\n       1 0 0 0];\u003c/pre\u003e\u003cp\u003eGood Luck!\u003c/p\u003e","function_template":"function b = ZeroDumping(a)\r\nb=a;\r\nend","test_suite":"%%\r\nx = 0;\r\ny_correct = [];\r\nassert(isequal(ZeroDumping(x),y_correct))\r\n\r\n%%\r\nx = 1;\r\ny_correct = 1;\r\nassert(isequal(ZeroDumping(x),y_correct))\r\n\r\n%%\r\nx = [1 0];\r\ny_correct = 1;\r\nassert(isequal(ZeroDumping(x),y_correct))\r\n\r\n%%\r\nx = [1 0 1 0;\r\n     0 0 1 0];\r\ny_correct = [1 0 1\r\n             0 0 1];\r\nassert(isequal(ZeroDumping(x),y_correct));\r\n\r\n%%\r\nx=[1,0,  -3, 1i,0;\r\n   2,0.3,2i, 0, 0;\r\n   0,0,   0, inf, 0;\r\n   0,0,   0, 0, 1];\r\ny_correct =x;% x(4,5) is useful, I don't want to dump it.\r\nassert(isequal(ZeroDumping(x),y_correct));\r\n\r\n%%\r\nx =[0\t0\t0\t0\t0\r\n0\t0\t0\t0\t0\r\n0\t0\t0\t0\t0\r\n0\t0\t0\t0\t0\r\n0\t0\t0\t0\teps];\r\ny_correct =x;\r\nassert(isequal(ZeroDumping(x),y_correct));\r\n\r\n%%\r\nx =[1\t1\t0\t0\t0\r\n    1\t0\t0\t0\t0\r\n    0\t0\t0\t3\t0\r\n    0\t0\t0\t0\t0\r\n    0\t0\t0\t0\t0];\r\ny_correct =[1\t1\t0\t0\r\n            1\t0\t0\t0\r\n            0\t0\t0\t3];\r\nassert(isequal(ZeroDumping(x),y_correct));\r\n\r\n%%\r\nx =[1\t1\t0\t0\t0\r\n    1\t0\t0\t0\t0\r\n    0\t0\t0\t3\t0\r\n    0\t0\t0\t0\tinf\r\n    0\t0\t0\t0\t0];\r\ny_correct =[1\t1\t0\t0\t0\r\n\t    1\t0\t0\t0\t0\r\n\t    0\t0\t0\t3\t0\r\n\t    0\t0\t0\t0\tinf];\r\nassert(isequal(ZeroDumping(x),y_correct));\r\n","published":true,"deleted":false,"likes_count":5,"comments_count":0,"created_by":7365,"edited_by":null,"edited_at":null,"deleted_by":null,"deleted_at":null,"solvers_count":283,"test_suite_updated_at":"2013-09-27T16:23:12.000Z","rescore_all_solutions":false,"group_id":23,"created_at":"2013-09-27T11:48:40.000Z","updated_at":"2026-05-04T03:14:52.000Z","published_at":"2013-09-27T12:56:24.000Z","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\u003eSometimes when I create a matrix, I use this syntax:\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[ a = zeros(1000,1000);]]\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 when the function ends, I find that I don't want all those zeros. Then I need another function to dump the extra zeros located to the south-east of the matrix.\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[ a1 = [1 2 0;\\n       0 3 0;\\n       0 0 0];]]\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\u003eI want to get a new matrix ,that is:\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[ b1 = [1 2;\\n       0 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\u003eAnother 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[ a2 = [1 2 0 4 0;\\n       2 3 0 5 0;\\n       3 4 0 6 0;\\n       1 0 0 0 0];\\n\\n b2 = [1 2 0 4;\\n       2 3 0 5;\\n       3 4 0 6;\\n       1 0 0 0];]]\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\u003eGood Luck!\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":"Matrix Manipulation II","count":1,"selected":false}],[{"value":"medium","count":1,"selected":false}]],"term":"tag:\"simplify\"","page":1,"per_page":50,"sort":"map(difficulty_value,0,0,999) asc"}}