![]() Subfunctions and private functions are, by design, limited in their visibility to other MATLAB functions. You can invoke a function directly from another function that is within its scope, but not from a function outside that scope. They are visible to other MATLAB entities within that scope, but not visible outside of it. If you evaluate the function with an argument of the double type, then the built-in function that takes a double argument is executed.Īllow Wider Access to Subfunctions and Private Functionsīy definition, all MATLAB functions have a certain scope. A function handle created for the abs function contains access information on all four of these function sources. See How MATLAB Determines Which Method to Call, for more information on how MATLAB selects overloaded functions.įor example, there are three built-in functions and one M-file function that define the abs function on the standard MATLAB path. When you evaluate an overloaded function handle, MATLAB follows the usual rules of selecting which method to evaluate, basing the selection on the argument types passed in the function call. ![]() A function handle stores the access to all of the overloaded sources, or methods, that are on the MATLAB path at the time the handle is created. When you pass a function handle as an argument into another function, then the function receiving the handle uses feval to evaluate the function handle.Ĭapture All Methods of An Overloaded Functionīecause many MATLAB functions are overloaded, a function handle often maps to a number of code sources (e.g., built-in code, M-files), that implement the function. ![]() You must use the MATLAB feval command to evaluate the function in a function handle. This is because the function performing the evaluation has all the information it needs within the function handle.įor the same reason, you can also evaluate a function handle even when the handle's function is no longer on the MATLAB search path. You can evaluate a function handle from within another function even if the handle's function is not in the scope of the evaluating function. The handle contains access information that enables the receiving function to call the function for which the handle was constructed. You can pass a function handle as an argument in a call to another function. Pass Function Access Information to Other Functions This section also includes an example of using a simple function handle. Manipulate handles in arrays, structures, and cell arrays.Improve performance in repeated operations.Reduce the number of files that define your functions.Ensure reliability when evaluating functions.Allow wider access to subfunctions and private functions.Capture all methods of an overloaded function.Pass function access information to other functions.It is the combination of which function methods are mapped to by the handle and what arguments the handle is evaluated with that determines which is the actual function that MATLAB dispatches to.įunction handles enable you to do all of the following: Other functions that might now be on the path or in scope are not considered. ![]() When you evaluate a function handle, MATLAB considers only those functions that were stored within the handle when it was created. When you create a handle to a function, MATLAB takes a snapshot of all built-in and M-file methods of that name that are on the MATLAB path and in scope at that time, and stores access information for all of those methods in the handle. It often represents a collection of function methods, overloaded to handle different argument types. It is then used in conjunction with feval to evaluate the function to which the handle belongs.Ī MATLAB function handle is more than just a reference to a function. Typically, a function handle is passed in an argument list to other functions. When you create a function handle, MATLAB stores in the handle all the information about the function that it needs to execute, or evaluate, it later on. Function Handles (Programming and Data Types) Programming and Data TypesĪ function handle is a MATLAB data type that contains information used in referencing a function.
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