Argument Definitions - MATLAB & Simulink - MathWorks Switzerland (2024)

Most functions do not require argument declarations or validation because MATLAB^® is an untyped language. However, if your function has wide usage and you need to verify the type, size, or other aspects of inputs to ensure that your code works as expected, you can define an arguments block.

function z = mySharedFunction(x,y,NameValueArgs) arguments x (1,1) double % scalar y double {mustBeVector,mustBePositive} NameValueArgs.A string NameValueArgs.B string = "default" end ...end

Argument Validation

• Function Argument Validation
  

  Declare argument class and size, and enforce restrictions on argument values.

  • Validate Required and Optional Positional Arguments
  • Validate Repeating Arguments
  • Validate Name-Value Arguments
• Argument Validation Functions
  

  Validate specific requirements of arguments using validation functions. Write your own functions to check for specific argument requirements.

  • Use Validation Functions to Avoid Unwanted Class and Size Conversions
  • Use nargin Functions During Argument Validation
• Check Function Inputs with validateattributes
  This example shows how to verify that the inputs toyour function conform to a set of requirements using the validateattributes function.
• Parse Function Inputs
  

  Define required and optional inputs, assign defaultsto optional inputs, and validate all inputs to a custom function usingthe Input Parser.

  • Input Parser Validation Functions

Number of Arguments

• Support Variable Number of Inputs
  Define a function that accepts a variable number ofinput arguments using varargin. The varargin argumentis a cell array that contains the function inputs, where each inputis in its own cell.
• Support Variable Number of Outputs
  Define a function that returns a variable number ofoutput arguments using varargout. Output varargout isa cell array that contains the function outputs, where each outputis in its own cell.
• Find Number of Function Arguments
  

  Use nargin and nargout todetermine how many input or output arguments your function receives.

  • Validate Number of Function Arguments
  • Checking Number of Arguments in Nested Functions

Pass-Through Inputs

• Ignore Inputs in Function Definitions
  If your function accepts a predefined set of inputs, but does not use all the inputs, use the tilde (~) operator to ignore them in your function definition.