{"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":379,"title":"Chromatic Tuner","description":"Given a frequency, return the number of cents difference between the given frequency and its nearest semitone (in 12-tone equal temperament with A440) as well as the semitone it is closest to (in scientific pitch notation, using # for sharp and using natural pitches whenever possible) with A440 referring to A4. Refer to the wikipedia articles below for more information.\r\n\r\nReferences:\r\n\r\n* \u003chttp://en.wikipedia.org/wiki/Semitone\u003e\r\n* \u003chttp://en.wikipedia.org/wiki/Equal_temperament\u003e\r\n* \u003chttp://en.wikipedia.org/wiki/Scientific_pitch_notation\u003e","description_html":"\u003cp\u003eGiven a frequency, return the number of cents difference between the given frequency and its nearest semitone (in 12-tone equal temperament with A440) as well as the semitone it is closest to (in scientific pitch notation, using # for sharp and using natural pitches whenever possible) with A440 referring to A4. Refer to the wikipedia articles below for more information.\u003c/p\u003e\u003cp\u003eReferences:\u003c/p\u003e\u003cul\u003e\u003cli\u003e\u003ca href=\"http://en.wikipedia.org/wiki/Semitone\"\u003ehttp://en.wikipedia.org/wiki/Semitone\u003c/a\u003e\u003c/li\u003e\u003cli\u003e\u003ca href=\"http://en.wikipedia.org/wiki/Equal_temperament\"\u003ehttp://en.wikipedia.org/wiki/Equal_temperament\u003c/a\u003e\u003c/li\u003e\u003cli\u003e\u003ca href=\"http://en.wikipedia.org/wiki/Scientific_pitch_notation\"\u003ehttp://en.wikipedia.org/wiki/Scientific_pitch_notation\u003c/a\u003e\u003c/li\u003e\u003c/ul\u003e","function_template":"function [c,s] = chromatic_tuner(f)\r\n  c = 0;\r\n  s = 'C#4';\r\nend","test_suite":"%%\r\n[c,s]=chromatic_tuner(440);\r\nassert(c==0 \u0026\u0026 strcmp(s,'A4'));\r\n\r\n%%\r\n[c,s]=chromatic_tuner(154);\r\nassert(c==-17 \u0026\u0026 strcmp(s,'D#3'));\r\n\r\n%%\r\n[c,s]=chromatic_tuner(478);\r\nassert(c==43 \u0026\u0026 strcmp(s,'A#4'));\r\n\r\n%%\r\n[c,s]=chromatic_tuner(795);\r\nassert(c==24 \u0026\u0026 strcmp(s,'G5'));\r\n\r\n%%\r\n[c,s]=chromatic_tuner(8651);\r\nassert(c==-43 \u0026\u0026 strcmp(s,'C#9'));\r\n\r\n%%\r\n[c,s]=chromatic_tuner(200);\r\nassert(c==35 \u0026\u0026 strcmp(s,'G3'));\r\n\r\n%%\r\n[c,s]=chromatic_tuner(11534);\r\nassert(c==-45 \u0026\u0026 strcmp(s,'F#9'));\r\n\r\n%%\r\n[c,s]=chromatic_tuner(163);\r\nassert(c==-19 \u0026\u0026 strcmp(s,'E3'));\r\n\r\n%%\r\n[c,s]=chromatic_tuner(7226);\r\nassert(c==45 \u0026\u0026 strcmp(s,'A8'));\r\n\r\n%%\r\n[c,s]=chromatic_tuner(2391);\r\nassert(c==30 \u0026\u0026 strcmp(s,'D7'));\r\n\r\n%%\r\n[c,s]=chromatic_tuner(17221);\r\nassert(c==49 \u0026\u0026 strcmp(s,'C10'));\r\n\r\n%%\r\n[c,s]=chromatic_tuner(11050);\r\nassert(c==-20 \u0026\u0026 strcmp(s,'F9'));\r\n\r\n%%\r\n[c,s]=chromatic_tuner(40865);\r\nassert(c==45 \u0026\u0026 strcmp(s,'D#11'));\r\n\r\n%%\r\n[c,s]=chromatic_tuner(37396);\r\nassert(c==-9 \u0026\u0026 strcmp(s,'D11'));\r\n\r\n%%\r\n[c,s]=chromatic_tuner(789);\r\nassert(c==11 \u0026\u0026 strcmp(s,'G5'));\r\n\r\n%%\r\n[c,s]=chromatic_tuner(9870);\r\nassert(c==-15 \u0026\u0026 strcmp(s,'D#9'));\r\n\r\n%%\r\n[c,s]=chromatic_tuner(306);\r\nassert(c==-29 \u0026\u0026 strcmp(s,'D#4'));\r\n\r\n%%\r\n[c,s]=chromatic_tuner(96);\r\nassert(c==-36 \u0026\u0026 strcmp(s,'G2'));\r\n\r\n%%\r\n[c,s]=chromatic_tuner(13513);\r\nassert(c==29 \u0026\u0026 strcmp(s,'G#9'));\r\n\r\n%%\r\n[c,s]=chromatic_tuner(2489);\r\nassert(c==0 \u0026\u0026 strcmp(s,'D#7'));\r\n\r\n%%\r\n[c,s]=chromatic_tuner(2166);\r\nassert(c==-41 \u0026\u0026 strcmp(s,'C#7'));","published":true,"deleted":false,"likes_count":0,"comments_count":4,"created_by":134,"edited_by":null,"edited_at":null,"deleted_by":null,"deleted_at":null,"solvers_count":15,"test_suite_updated_at":"2012-02-24T05:07:45.000Z","rescore_all_solutions":false,"group_id":1,"created_at":"2012-02-22T01:01:42.000Z","updated_at":"2026-05-25T22:34:41.000Z","published_at":"2012-02-24T05:07:45.000Z","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\u003eGiven a frequency, return the number of cents difference between the given frequency and its nearest semitone (in 12-tone equal temperament with A440) as well as the semitone it is closest to (in scientific pitch notation, using # for sharp and using natural pitches whenever possible) with A440 referring to A4. Refer to the wikipedia articles below for more information.\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\u003eReferences:\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:p\u003e\u003cw:p\u003e\u003cw:pPr\u003e\u003cw:pStyle w:val=\\\"ListParagraph\\\"/\u003e\u003cw:numPr\u003e\u003cw:numId w:val=\\\"1\\\"/\u003e\u003c/w:numPr\u003e\u003c/w:pPr\u003e\u003cw:hyperlink w:docLocation=\\\"http://en.wikipedia.org/wiki/Semitone\\\"\u003e\u003cw:r\u003e\u003cw:t\u003ehttp://en.wikipedia.org/wiki/Semitone\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:hyperlink\u003e\u003c/w:p\u003e\u003cw:p\u003e\u003cw:pPr\u003e\u003cw:pStyle w:val=\\\"ListParagraph\\\"/\u003e\u003cw:numPr\u003e\u003cw:numId w:val=\\\"1\\\"/\u003e\u003c/w:numPr\u003e\u003c/w:pPr\u003e\u003cw:hyperlink w:docLocation=\\\"http://en.wikipedia.org/wiki/Equal_temperament\\\"\u003e\u003cw:r\u003e\u003cw:t\u003ehttp://en.wikipedia.org/wiki/Equal_temperament\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:hyperlink\u003e\u003c/w:p\u003e\u003cw:p\u003e\u003cw:pPr\u003e\u003cw:pStyle w:val=\\\"ListParagraph\\\"/\u003e\u003cw:numPr\u003e\u003cw:numId w:val=\\\"1\\\"/\u003e\u003c/w:numPr\u003e\u003c/w:pPr\u003e\u003cw:hyperlink w:docLocation=\\\"http://en.wikipedia.org/wiki/Scientific_pitch_notation\\\"\u003e\u003cw:r\u003e\u003cw:t\u003ehttp://en.wikipedia.org/wiki/Scientific_pitch_notation\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\"}]}"}],"problem_search":{"problems":[{"id":379,"title":"Chromatic Tuner","description":"Given a frequency, return the number of cents difference between the given frequency and its nearest semitone (in 12-tone equal temperament with A440) as well as the semitone it is closest to (in scientific pitch notation, using # for sharp and using natural pitches whenever possible) with A440 referring to A4. Refer to the wikipedia articles below for more information.\r\n\r\nReferences:\r\n\r\n* \u003chttp://en.wikipedia.org/wiki/Semitone\u003e\r\n* \u003chttp://en.wikipedia.org/wiki/Equal_temperament\u003e\r\n* \u003chttp://en.wikipedia.org/wiki/Scientific_pitch_notation\u003e","description_html":"\u003cp\u003eGiven a frequency, return the number of cents difference between the given frequency and its nearest semitone (in 12-tone equal temperament with A440) as well as the semitone it is closest to (in scientific pitch notation, using # for sharp and using natural pitches whenever possible) with A440 referring to A4. Refer to the wikipedia articles below for more information.\u003c/p\u003e\u003cp\u003eReferences:\u003c/p\u003e\u003cul\u003e\u003cli\u003e\u003ca href=\"http://en.wikipedia.org/wiki/Semitone\"\u003ehttp://en.wikipedia.org/wiki/Semitone\u003c/a\u003e\u003c/li\u003e\u003cli\u003e\u003ca href=\"http://en.wikipedia.org/wiki/Equal_temperament\"\u003ehttp://en.wikipedia.org/wiki/Equal_temperament\u003c/a\u003e\u003c/li\u003e\u003cli\u003e\u003ca href=\"http://en.wikipedia.org/wiki/Scientific_pitch_notation\"\u003ehttp://en.wikipedia.org/wiki/Scientific_pitch_notation\u003c/a\u003e\u003c/li\u003e\u003c/ul\u003e","function_template":"function [c,s] = chromatic_tuner(f)\r\n  c = 0;\r\n  s = 'C#4';\r\nend","test_suite":"%%\r\n[c,s]=chromatic_tuner(440);\r\nassert(c==0 \u0026\u0026 strcmp(s,'A4'));\r\n\r\n%%\r\n[c,s]=chromatic_tuner(154);\r\nassert(c==-17 \u0026\u0026 strcmp(s,'D#3'));\r\n\r\n%%\r\n[c,s]=chromatic_tuner(478);\r\nassert(c==43 \u0026\u0026 strcmp(s,'A#4'));\r\n\r\n%%\r\n[c,s]=chromatic_tuner(795);\r\nassert(c==24 \u0026\u0026 strcmp(s,'G5'));\r\n\r\n%%\r\n[c,s]=chromatic_tuner(8651);\r\nassert(c==-43 \u0026\u0026 strcmp(s,'C#9'));\r\n\r\n%%\r\n[c,s]=chromatic_tuner(200);\r\nassert(c==35 \u0026\u0026 strcmp(s,'G3'));\r\n\r\n%%\r\n[c,s]=chromatic_tuner(11534);\r\nassert(c==-45 \u0026\u0026 strcmp(s,'F#9'));\r\n\r\n%%\r\n[c,s]=chromatic_tuner(163);\r\nassert(c==-19 \u0026\u0026 strcmp(s,'E3'));\r\n\r\n%%\r\n[c,s]=chromatic_tuner(7226);\r\nassert(c==45 \u0026\u0026 strcmp(s,'A8'));\r\n\r\n%%\r\n[c,s]=chromatic_tuner(2391);\r\nassert(c==30 \u0026\u0026 strcmp(s,'D7'));\r\n\r\n%%\r\n[c,s]=chromatic_tuner(17221);\r\nassert(c==49 \u0026\u0026 strcmp(s,'C10'));\r\n\r\n%%\r\n[c,s]=chromatic_tuner(11050);\r\nassert(c==-20 \u0026\u0026 strcmp(s,'F9'));\r\n\r\n%%\r\n[c,s]=chromatic_tuner(40865);\r\nassert(c==45 \u0026\u0026 strcmp(s,'D#11'));\r\n\r\n%%\r\n[c,s]=chromatic_tuner(37396);\r\nassert(c==-9 \u0026\u0026 strcmp(s,'D11'));\r\n\r\n%%\r\n[c,s]=chromatic_tuner(789);\r\nassert(c==11 \u0026\u0026 strcmp(s,'G5'));\r\n\r\n%%\r\n[c,s]=chromatic_tuner(9870);\r\nassert(c==-15 \u0026\u0026 strcmp(s,'D#9'));\r\n\r\n%%\r\n[c,s]=chromatic_tuner(306);\r\nassert(c==-29 \u0026\u0026 strcmp(s,'D#4'));\r\n\r\n%%\r\n[c,s]=chromatic_tuner(96);\r\nassert(c==-36 \u0026\u0026 strcmp(s,'G2'));\r\n\r\n%%\r\n[c,s]=chromatic_tuner(13513);\r\nassert(c==29 \u0026\u0026 strcmp(s,'G#9'));\r\n\r\n%%\r\n[c,s]=chromatic_tuner(2489);\r\nassert(c==0 \u0026\u0026 strcmp(s,'D#7'));\r\n\r\n%%\r\n[c,s]=chromatic_tuner(2166);\r\nassert(c==-41 \u0026\u0026 strcmp(s,'C#7'));","published":true,"deleted":false,"likes_count":0,"comments_count":4,"created_by":134,"edited_by":null,"edited_at":null,"deleted_by":null,"deleted_at":null,"solvers_count":15,"test_suite_updated_at":"2012-02-24T05:07:45.000Z","rescore_all_solutions":false,"group_id":1,"created_at":"2012-02-22T01:01:42.000Z","updated_at":"2026-05-25T22:34:41.000Z","published_at":"2012-02-24T05:07:45.000Z","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\u003eGiven a frequency, return the number of cents difference between the given frequency and its nearest semitone (in 12-tone equal temperament with A440) as well as the semitone it is closest to (in scientific pitch notation, using # for sharp and using natural pitches whenever possible) with A440 referring to A4. 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