Let's illustrate the problem with a very simple example using the Date<\/tt><\/a> class available in the java.util<\/tt> package. If you never worked with Java Libraries in MATLAB, you can get an overview in this section of the documentation<\/a>\r\n\r\n In MATLAB, I can create a java.util.Date<\/tt> object:<\/p>\r\n\r\n Once the object is in the base workspace, I can call any of its method:<\/p>\r\n\r\n This is simple... but in Simulink how to create the object once and access its methods every step?<\/p>\r\n\r\n The solution: A persistent object in the MATLAB Function Block<\/strong><\/p>\r\n\r\n One easy way to implement something like that is using the MATLAB function block<\/a>.<\/p>\r\n\r\n The MATLAB Function block works by converting MATLAB code to C code and executing it during the simulation. The MATLAB function block can only generate code for a subset of the MATLAB language. However, it can call outside the generated C code, back to MATLAB, to run the expressions that do not support code generation. These functions are referred to as extrinsic functions<\/em>, as they execute outside the generated C code. This is useful if your block will only be used for simulation.<\/p>\r\n\r\n When I use the MATLAB Function block for simulation only applications like this one (I do not need to generate code for an embedded system), I like to make all my code extrinsic. That way I do not need to worry about MATLAB Code Design Considerations for Code Generation<\/a>.<\/p>\r\n\r\n To do this, I create a separate MATLAB function file and make it extrinsic. The code in the MATLAB Function block looks like:<\/p>\r\n\r\n In the extrinsic function myWrapper.m<\/tt>, I manage the object and implement my algorithm. To keep the object properties from step to step, I make it persistent<\/a>, and I initialize it only once using the isempty<\/a> function:<\/p>\r\n\r\n and that's it... I can now access all the methods of this object and its properties remain persistent from step to step.<\/p>\r\n\r\n Now it's your turn<\/strong><\/p>\r\n\r\n Note that this is not the only way to implement such functionality. A MATLAB Level 2 S-Function<\/a> would also give similar results.<\/p>\r\n\r\n Give that a try and let us know what you think by leaving a comment here<\/a>.<\/p>\r\n\r\n\r\n\r\n\r\n","protected":false},"excerpt":{"rendered":" Recently, I spoke with a user who needed to interface a Simulink model with an external flight simulator implemented as java classes. He was able to exchange data with his simulator at the MATLAB... read more >><\/a><\/p>","protected":false},"author":41,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":[],"categories":[102,87,10,33],"tags":[356],"_links":{"self":[{"href":"https:\/\/blogs.mathworks.com\/simulink\/wp-json\/wp\/v2\/posts\/3117"}],"collection":[{"href":"https:\/\/blogs.mathworks.com\/simulink\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blogs.mathworks.com\/simulink\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blogs.mathworks.com\/simulink\/wp-json\/wp\/v2\/users\/41"}],"replies":[{"embeddable":true,"href":"https:\/\/blogs.mathworks.com\/simulink\/wp-json\/wp\/v2\/comments?post=3117"}],"version-history":[{"count":27,"href":"https:\/\/blogs.mathworks.com\/simulink\/wp-json\/wp\/v2\/posts\/3117\/revisions"}],"predecessor-version":[{"id":3161,"href":"https:\/\/blogs.mathworks.com\/simulink\/wp-json\/wp\/v2\/posts\/3117\/revisions\/3161"}],"wp:attachment":[{"href":"https:\/\/blogs.mathworks.com\/simulink\/wp-json\/wp\/v2\/media?parent=3117"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blogs.mathworks.com\/simulink\/wp-json\/wp\/v2\/categories?post=3117"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blogs.mathworks.com\/simulink\/wp-json\/wp\/v2\/tags?post=3117"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}![\"Creating](\"https:\/\/blogs.mathworks.com\/images\/seth\/2013Q4\/objectCreation.png\")
<\/p>\r\n\r\n![\"Calling](\"https:\/\/blogs.mathworks.com\/images\/seth\/2013Q4\/objectMethods.png\")
<\/p>\r\n\r\n![\"MATLAB](\"https:\/\/blogs.mathworks.com\/images\/seth\/2013Q4\/MlFcnBlockinModel.png\")
<\/p>\r\n\r\n![\"MATLAB](\"https:\/\/blogs.mathworks.com\/images\/seth\/2013Q4\/MlFcnBlock.png\")
<\/p>\r\n\r\n![\"MATLAB](\"https:\/\/blogs.mathworks.com\/images\/seth\/2013Q4\/wrapperCode.png\")
<\/p>\r\n\r\n<\/div>