That function is a helper function created for the example that you linked in your comment. It is not a regular function in the toolbox. You could make a copy of that function (see the "Supporting Functions" section in the example) or open the example in MATLAB (navigate to it in the Help Browser then click the link in the upper-right corner of the example page.)
Also, please limit the number of tags you use to the most relevant ones for your question. As an example of some that existed before I removed them, "string", "vector", and "script" aren't relevant at all for this question.