{"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":1010,"title":"Create a \"map\" of 2D wavelet coefficients","description":"Generate a matrix that for an image of size r*2^S by c*2^S indicates index of the wavelet subbands after \u003chttp://en.wikipedia.org/wiki/Discrete_wavelet_transform 2D Discrete Wavelet Transform\u003e. Subbands are indexed from the lowest to highest frequency clockwise.\r\n\r\nAs inputs number of scales S and size (r x c) of the lowest frequency subband are given.\r\n\r\nFor example (2 scales and r=1,  c=1) : \r\n\r\n  w = createDWTBlockMap(2, 1, 1)\r\n\r\nShould produce:\r\n\r\n  1     2     5     5\r\n  4     3     5     5\r\n  7     7     6     6\r\n  7     7     6     6\r\n\r\n1 (or 1s) in the top-left corner indicating approximation band and then 2,3,4,..,3*S+1 the other bands.","description_html":"\u003cp\u003eGenerate a matrix that for an image of size r*2^S by c*2^S indicates index of the wavelet subbands after \u003ca href=\"http://en.wikipedia.org/wiki/Discrete_wavelet_transform\"\u003e2D Discrete Wavelet Transform\u003c/a\u003e. Subbands are indexed from the lowest to highest frequency clockwise.\u003c/p\u003e\u003cp\u003eAs inputs number of scales S and size (r x c) of the lowest frequency subband are given.\u003c/p\u003e\u003cp\u003eFor example (2 scales and r=1,  c=1) :\u003c/p\u003e\u003cpre class=\"language-matlab\"\u003ew = createDWTBlockMap(2, 1, 1)\r\n\u003c/pre\u003e\u003cp\u003eShould produce:\u003c/p\u003e\u003cpre class=\"language-matlab\"\u003e1     2     5     5\r\n4     3     5     5\r\n7     7     6     6\r\n7     7     6     6\r\n\u003c/pre\u003e\u003cp\u003e1 (or 1s) in the top-left corner indicating approximation band and then 2,3,4,..,3*S+1 the other bands.\u003c/p\u003e","function_template":"function w = createDWTBlockMap(S, r, c)\r\n\r\nend","test_suite":"%%\r\nw = createDWTBlockMap(0, 1, 1)\r\ny_correct = 1;\r\nassert(isequal(w,y_correct))\r\n%%\r\nw = createDWTBlockMap(2, 1, 1)\r\ny_correct = [     1     2     5     5\r\n     4     3     5     5\r\n     7     7     6     6\r\n     7     7     6     6];\r\nassert(isequal(w,y_correct))\r\n%%\r\nw = createDWTBlockMap(2, 2, 1)\r\ny_correct = [\r\n     1     2     5     5\r\n     1     2     5     5\r\n     4     3     5     5\r\n     4     3     5     5\r\n     7     7     6     6\r\n     7     7     6     6\r\n     7     7     6     6\r\n     7     7     6     6];\r\nassert(isequal(w,y_correct))\r\n%%\r\nw = createDWTBlockMap(2, 1, 2)\r\ny_correct = [\r\n     1     1     2     2     5     5     5     5\r\n     4     4     3     3     5     5     5     5\r\n     7     7     7     7     6     6     6     6\r\n     7     7     7     7     6     6     6     6];\r\nassert(isequal(w,y_correct))\r\n%%\r\nw = createDWTBlockMap(1, 3, 3)\r\ny_correct =     [ \r\n     1     1     1     2     2     2\r\n     1     1     1     2     2     2\r\n     1     1     1     2     2     2\r\n     4     4     4     3     3     3\r\n     4     4     4     3     3     3\r\n     4     4     4     3     3     3];\r\nassert(isequal(w,y_correct))\r\n%%\r\nw = createDWTBlockMap(0, 3, 3);\r\ny_correct = ones(3);\r\nassert(isequal(w,y_correct))","published":true,"deleted":false,"likes_count":0,"comments_count":0,"created_by":6084,"edited_by":null,"edited_at":null,"deleted_by":null,"deleted_at":null,"solvers_count":5,"test_suite_updated_at":null,"rescore_all_solutions":false,"group_id":1,"created_at":"2012-10-25T16:25:49.000Z","updated_at":"2026-05-26T06:11:42.000Z","published_at":"2012-10-25T16:40:19.000Z","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\u003eGenerate a matrix that for an image of size r*2^S by c*2^S indicates index of the wavelet subbands after\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://en.wikipedia.org/wiki/Discrete_wavelet_transform\\\"\u003e\u003cw:r\u003e\u003cw:t\u003e2D Discrete Wavelet Transform\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:hyperlink\u003e\u003cw:r\u003e\u003cw:t\u003e. Subbands are indexed from the lowest to highest frequency clockwise.\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\u003eAs inputs number of scales S and size (r x c) of the lowest frequency subband are given.\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 (2 scales and r=1, c=1) :\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[w = createDWTBlockMap(2, 1, 1)]]\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\u003eShould produce:\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[1     2     5     5\\n4     3     5     5\\n7     7     6     6\\n7     7     6     6]]\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\u003e1 (or 1s) in the top-left corner indicating approximation band and then 2,3,4,..,3*S+1 the other bands.\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":1010,"title":"Create a \"map\" of 2D wavelet coefficients","description":"Generate a matrix that for an image of size r*2^S by c*2^S indicates index of the wavelet subbands after \u003chttp://en.wikipedia.org/wiki/Discrete_wavelet_transform 2D Discrete Wavelet Transform\u003e. Subbands are indexed from the lowest to highest frequency clockwise.\r\n\r\nAs inputs number of scales S and size (r x c) of the lowest frequency subband are given.\r\n\r\nFor example (2 scales and r=1,  c=1) : \r\n\r\n  w = createDWTBlockMap(2, 1, 1)\r\n\r\nShould produce:\r\n\r\n  1     2     5     5\r\n  4     3     5     5\r\n  7     7     6     6\r\n  7     7     6     6\r\n\r\n1 (or 1s) in the top-left corner indicating approximation band and then 2,3,4,..,3*S+1 the other bands.","description_html":"\u003cp\u003eGenerate a matrix that for an image of size r*2^S by c*2^S indicates index of the wavelet subbands after \u003ca href=\"http://en.wikipedia.org/wiki/Discrete_wavelet_transform\"\u003e2D Discrete Wavelet Transform\u003c/a\u003e. Subbands are indexed from the lowest to highest frequency clockwise.\u003c/p\u003e\u003cp\u003eAs inputs number of scales S and size (r x c) of the lowest frequency subband are given.\u003c/p\u003e\u003cp\u003eFor example (2 scales and r=1,  c=1) :\u003c/p\u003e\u003cpre class=\"language-matlab\"\u003ew = createDWTBlockMap(2, 1, 1)\r\n\u003c/pre\u003e\u003cp\u003eShould produce:\u003c/p\u003e\u003cpre class=\"language-matlab\"\u003e1     2     5     5\r\n4     3     5     5\r\n7     7     6     6\r\n7     7     6     6\r\n\u003c/pre\u003e\u003cp\u003e1 (or 1s) in the top-left corner indicating approximation band and then 2,3,4,..,3*S+1 the other bands.\u003c/p\u003e","function_template":"function w = createDWTBlockMap(S, r, c)\r\n\r\nend","test_suite":"%%\r\nw = createDWTBlockMap(0, 1, 1)\r\ny_correct = 1;\r\nassert(isequal(w,y_correct))\r\n%%\r\nw = createDWTBlockMap(2, 1, 1)\r\ny_correct = [     1     2     5     5\r\n     4     3     5     5\r\n     7     7     6     6\r\n     7     7     6     6];\r\nassert(isequal(w,y_correct))\r\n%%\r\nw = createDWTBlockMap(2, 2, 1)\r\ny_correct = [\r\n     1     2     5     5\r\n     1     2     5     5\r\n     4     3     5     5\r\n     4     3     5     5\r\n     7     7     6     6\r\n     7     7     6     6\r\n     7     7     6     6\r\n     7     7     6     6];\r\nassert(isequal(w,y_correct))\r\n%%\r\nw = createDWTBlockMap(2, 1, 2)\r\ny_correct = [\r\n     1     1     2     2     5     5     5     5\r\n     4     4     3     3     5     5     5     5\r\n     7     7     7     7     6     6     6     6\r\n     7     7     7     7     6     6     6     6];\r\nassert(isequal(w,y_correct))\r\n%%\r\nw = createDWTBlockMap(1, 3, 3)\r\ny_correct =     [ \r\n     1     1     1     2     2     2\r\n     1     1     1     2     2     2\r\n     1     1     1     2     2     2\r\n     4     4     4     3     3     3\r\n     4     4     4     3     3     3\r\n     4     4     4     3     3     3];\r\nassert(isequal(w,y_correct))\r\n%%\r\nw = createDWTBlockMap(0, 3, 3);\r\ny_correct = ones(3);\r\nassert(isequal(w,y_correct))","published":true,"deleted":false,"likes_count":0,"comments_count":0,"created_by":6084,"edited_by":null,"edited_at":null,"deleted_by":null,"deleted_at":null,"solvers_count":5,"test_suite_updated_at":null,"rescore_all_solutions":false,"group_id":1,"created_at":"2012-10-25T16:25:49.000Z","updated_at":"2026-05-26T06:11:42.000Z","published_at":"2012-10-25T16:40:19.000Z","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\u003eGenerate a matrix that for an image of size r*2^S by c*2^S indicates index of the wavelet subbands after\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://en.wikipedia.org/wiki/Discrete_wavelet_transform\\\"\u003e\u003cw:r\u003e\u003cw:t\u003e2D Discrete Wavelet Transform\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:hyperlink\u003e\u003cw:r\u003e\u003cw:t\u003e. Subbands are indexed from the lowest to highest frequency clockwise.\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\u003eAs inputs number of scales S and size (r x c) of the lowest frequency subband are given.\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 (2 scales and r=1, c=1) :\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[w = createDWTBlockMap(2, 1, 1)]]\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\u003eShould produce:\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[1     2     5     5\\n4     3     5     5\\n7     7     6     6\\n7     7     6     6]]\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\u003e1 (or 1s) in the top-left corner indicating approximation band and then 2,3,4,..,3*S+1 the other bands.\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":"hard","count":1,"selected":false}]],"term":"tag:\"wavelets\"","page":1,"per_page":50,"sort":"map(difficulty_value,0,0,999) asc"}}