Function Precedence Order - MATLAB & Simulink (original) (raw)

This topic explains how MATLAB® determines which function to call when multiple functions in the current scope have the same name. The current scope includes the current file, an optional private subfolder relative to the currently running function, the current folder, and the MATLAB path.

MATLAB uses this precedence order:

  1. Variables
    Before assuming that a name matches a function, MATLAB checks for a variable with that name in the current workspace.
    Note
    If you create a variable with the same name as a function, MATLAB cannot run that function until you clear the variable from memory.
  2. Function or class whose name matches an explicitly imported name
    The import function allows functions with compound names (names comprised of several parts joined by dots) to be called using only the final part of the compound name. When a function name matches an explicit (non-wildcard) imported function,​ MATLAB uses the imported compound name and gives it precedence over all other functions with the same name.
  3. Nested functions within the current function
  4. Local functions within the current file
  5. Function or class whose name matches a wildcard-based imported name
    When a function name matches a wildcard-based imported function,​ MATLAB uses the imported compound name and gives it precedence over all other functions with the same name,​ except for nested and local functions.
  6. Private functions
    Private functions are functions in a subfolder namedprivate that is immediately below the folder of the currently running file.
  7. Object functions
    An object function accepts a particular class of object in its input argument list. When there are multiple object functions with the same name, MATLAB checks the classes of the input arguments to determine which function to use.
  8. Class constructors in @-folders
    MATLAB uses class constructors to create a variety of objects (such astimeseries or audioplayer), and you can define your own classes using object-oriented programming. For example, if you create a class folder @polynom and a constructor function@polynom/polynom.m, the constructor takes precedence over other functions named polynom.m anywhere on the path.
    Note
    The precedence of classes defined in @-folders over functions with the same name will be removed in a future release. For additional information see Class Precedence and MATLAB Path.
  9. Loaded Simulink® models
  10. Functions in the current folder
  11. Functions elsewhere on the path, in order of appearance

When determining the precedence of functions within the same folder, MATLAB considers the file type, in this order:

  1. Built-in function
  2. MEX-function
  3. Simulink model files that are not loaded, with file types in this order:
    1. SLX file
    2. MDL file
  4. Stateflow® chart with a .sfx extension
  5. App file (.mlapp) created using MATLAB App Designer
  6. Program file with a .mlx extension
  7. P-file (that is, an encoded program file with a.p extension)
  8. Program file with a .m extension

For example, if MATLAB finds a .m file and a P-file with the same name in the same folder, it uses the P-file. Because P-files are not automatically regenerated, make sure that you regenerate the P-file whenever you edit the program file.

To determine the function MATLAB calls for a particular input, include the function name and the input in a call to the which function.

Change in Rules For Function Precedence Order

Starting in R2019b, MATLAB changes the rules for name resolution, impacting the precedence order of variables, nested functions, local functions, and external functions. For information about the changes and tips for updating your code, see Update Code for R2019b Changes to Function Precedence Order.

The behavior of the import function has changed.

See Also

import