{"id":213,"date":"2010-01-12T15:03:51","date_gmt":"2010-01-12T15:03:51","guid":{"rendered":"https:\/\/blogs.mathworks.com\/loren\/2010\/01\/12\/the-chebfun-project\/"},"modified":"2016-08-01T10:51:48","modified_gmt":"2016-08-01T15:51:48","slug":"the-chebfun-project","status":"publish","type":"post","link":"https:\/\/blogs.mathworks.com\/loren\/2010\/01\/12\/the-chebfun-project\/","title":{"rendered":"The chebfun Project"},"content":{"rendered":"<div class=\"content\">\n<p>Nick Trefethen and a team of colleagues have created a MATLAB software package called <tt>chebfun<\/tt>. Version 2 is now available on the <a href=\"https:\/\/www.mathworks.com\/matlabcentral\/fileexchange\/23972-chebfun-v4-old-version--please-download-current-version-instead\">File Exchange<\/a>. Version 3 is available on <a href=\"http:\/\/www.chebfun.org\/\">their site<\/a>. The package is designed to have syntax very much like regular vector notation in MATLAB, though the entities represent functions.<br \/>\nThey accomplished this using some of the newer features of the <a href=\"https:\/\/www.mathworks.com\/help\/releases\/R2009b\/techdoc\/matlab_oop\/ug_intropage.html\">MATLAB object system<\/a>. Basically the project extends familiar notions for numbers to the realm of continuous and piecewise continuous functions.<\/p>\n<p>&nbsp;<\/p>\n<h3>Contents<\/h3>\n<div>\n<ul>\n<li><a href=\"#1\">User Guide<\/a><\/li>\n<li><a href=\"#2\">Recent Additions<\/a><\/li>\n<li><a href=\"#3\">What Do You Use for Basis Functions and Approximation?<\/a><\/li>\n<\/ul>\n<\/div>\n<h3>User Guide<a name=\"1\"><\/a><\/h3>\n<p>The user guide, on-line, comprises published MATLAB code, and the source is available as well. Chapters include examples<br \/>\nand a set of references for the benefit of those who wish to dive more deeply into the subject matter.<\/p>\n<h3>Recent Additions<a name=\"2\"><\/a><\/h3>\n<p>Recent additions include chapters on how to work with infinities (intervals and values) and singularities and nonlinear ODEs.<br \/>\nExamples on <a href=\"http:\/\/www.chebfun.org\/examples\/\">this page<\/a> include how, in version 3, to work with unbounded functions and intervals.<\/p>\n<h3>What Do You Use for Basis Functions and Approximation?<a name=\"3\"><\/a><\/h3>\n<p>Many people use splines as basis functions for approximations, solving differential equations, and so on. Some people use<br \/>\nwavelets for similar purposes. The package discussed here relies on Chebyshev functions. What do you use? Let me know <a href=\"https:\/\/blogs.mathworks.com\/loren\/?p=213#respond\">here<\/a>.<\/p>\n<p><script>\/\/ <![CDATA[\nfunction grabCode_0916a59e31e94f26b3385b283c70ef6c() {\n        \/\/ Remember the title so we can use it in the new page\n        title = document.title;\n\n        \/\/ Break up these strings so that their presence\n        \/\/ in the Javascript doesn't mess up the search for\n        \/\/ the MATLAB code.\n        t1='0916a59e31e94f26b3385b283c70ef6c ' + '##### ' + 'SOURCE BEGIN' + ' #####';\n        t2='##### ' + 'SOURCE END' + ' #####' + ' 0916a59e31e94f26b3385b283c70ef6c';\n    \n        b=document.getElementsByTagName('body')[0];\n        i1=b.innerHTML.indexOf(t1)+t1.length;\n        i2=b.innerHTML.indexOf(t2);\n \n        code_string = b.innerHTML.substring(i1, i2);\n        code_string = code_string.replace(\/REPLACE_WITH_DASH_DASH\/g,'--');\n\n        \/\/ Use \/x3C\/g instead of the less-than character to avoid errors \n        \/\/ in the XML parser.\n        \/\/ Use '\\x26#60;' instead of '<' so that the XML parser\n        \/\/ doesn't go ahead and substitute the less-than character. \n        code_string = code_string.replace(\/\\x3C\/g, '\\x26#60;');\n\n        author = 'Loren Shure';\n        copyright = 'Copyright 2010 The MathWorks, Inc.';\n\n        w = window.open();\n        d = w.document;\n        d.write('\n\n\n\n<pre>\\n');\r\n        d.write(code_string);\r\n\r\n        \/\/ Add author and copyright lines at the bottom if specified.\r\n        if ((author.length > 0) || (copyright.length > 0)) {\r\n            d.writeln('');\r\n            d.writeln('%%');\r\n            if (author.length > 0) {\r\n                d.writeln('% _' + author + '_');\r\n            }\r\n            if (copyright.length > 0) {\r\n                d.writeln('% _' + copyright + '_');\r\n            }\r\n        }\r\n\r\n        d.write('<\/pre>\n\n\n\n\n\\n');\n      \n      d.title = title + ' (MATLAB code)';\n      d.close();\n      }\n\/\/ ]]><\/script><\/p>\n<p style=\"text-align: right; font-size: xx-small; font-weight: lighter; font-style: italic; color: gray;\">\n<a><span style=\"font-size: x-small; font-style: italic;\">Get<br \/>\nthe MATLAB code<br \/>\n<noscript>(requires JavaScript)<\/noscript><\/span><\/a><\/p>\n<p>Published with MATLAB\u00ae 7.9<\/p>\n<\/div>\n<p><!--\n0916a59e31e94f26b3385b283c70ef6c ##### SOURCE BEGIN #####\n%% The chebfun Project\n% Nick Trefethen and a <http:\/\/www2.maths.ox.ac.uk\/chebfun\/team.html team>\n% of colleagues have created a MATLAB software package called\n% |chebfun|.  Version 2 is now available\n% on the\n% <https:\/\/www.mathworks.com\/matlabcentral\/fileexchange\/23972-chebfun-v4-old-version--please-download-current-version-instead File Exchange>.\n% Version 3 is available on <http:\/\/www.maths.ox.ac.uk\/chebfun\/ their site>.\n% The package is designed to have syntax very much like regular vector\n% notation in MATLAB, though the entities represent functions.  They\n% accomplished this using some of the newer features of the\n% <https:\/\/www.mathworks.com\/help\/releases\/R2009b\/techdoc\/matlab_oop\/ug_intropage.html MATLAB object system>.\n% Basically the project extends familiar notions for numbers to the\n% realm of continuous and piecewise continuous functions.\n\n%% User Guide\n% The user guide, on-line, comprises published MATLAB code, and the source\n% is available as well.  Chapters include examples and a\n% set of references for the benefit of those who wish to dive more deeply\n% into the subject matter.\n\n%% Recent Additions\n% Recent additions include chapters on how to work with infinities\n% (intervals and values) and singularities and nonlinear ODEs.\n% Examples on <http:\/\/www2.maths.ox.ac.uk\/chebfun\/examples.html this page>\n% include how, in version 3, to work with unbounded functions and\n% intervals.\n\n%% What Do You Use for Basis Functions and Approximation?\n% Many people use splines as basis functions for approximations, solving\n% differential equations, and so on.  Some people use wavelets for similar\n% purposes.  The package discussed here relies on Chebyshev functions.\n% What do you use?  Let me know\n% <https:\/\/blogs.mathworks.com\/loren\/?p=213#respond here>.\n##### SOURCE END ##### 0916a59e31e94f26b3385b283c70ef6c\n--><\/p>\n","protected":false},"excerpt":{"rendered":"<p>\nNick Trefethen and a team of colleagues have created a MATLAB software package called chebfun. Version 2 is now available on the File Exchange. Version 3 is available on their site. The package is... <a class=\"read-more\" href=\"https:\/\/blogs.mathworks.com\/loren\/2010\/01\/12\/the-chebfun-project\/\">read more >><\/a><\/p>\n","protected":false},"author":39,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":[],"categories":[13],"tags":[],"_links":{"self":[{"href":"https:\/\/blogs.mathworks.com\/loren\/wp-json\/wp\/v2\/posts\/213"}],"collection":[{"href":"https:\/\/blogs.mathworks.com\/loren\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blogs.mathworks.com\/loren\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blogs.mathworks.com\/loren\/wp-json\/wp\/v2\/users\/39"}],"replies":[{"embeddable":true,"href":"https:\/\/blogs.mathworks.com\/loren\/wp-json\/wp\/v2\/comments?post=213"}],"version-history":[{"count":2,"href":"https:\/\/blogs.mathworks.com\/loren\/wp-json\/wp\/v2\/posts\/213\/revisions"}],"predecessor-version":[{"id":1875,"href":"https:\/\/blogs.mathworks.com\/loren\/wp-json\/wp\/v2\/posts\/213\/revisions\/1875"}],"wp:attachment":[{"href":"https:\/\/blogs.mathworks.com\/loren\/wp-json\/wp\/v2\/media?parent=213"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blogs.mathworks.com\/loren\/wp-json\/wp\/v2\/categories?post=213"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blogs.mathworks.com\/loren\/wp-json\/wp\/v2\/tags?post=213"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}