Programming and Data Types

Function Handle Operations

MATLAB provides two functions that enable you to convert between a function handle and a function name string. It also provides functions for testing to see if a variable holds a function handle, and for comparing function handles.

Converting Function Handles to Function Names

If you need to perform string operations, such as string comparison or display, on a function handle, you can use func2str to obtain the function name in string format. To convert a sin function handle to a string

• fhandle = @sin;
  
  func2str(fhandle)
  ans =
      sin
  

Note    The func2str command does not operate on nonscalar function handles. Passing a nonscalar function handle to func2str results in an error.

Example - Displaying the Function Name in an Error Message

The catcherr function shown here accepts function handle and data arguments and attempts to evaluate the function through its handle. If the function fails to execute, catcherr uses sprintf to display an error message giving the name of the failing function. The function name must be a string for sprintf to display it. The code derives the function name from the function handle using func2str.

• function catcherr(func, data)
  try
      ans = feval(func, data);
      disp('Answer is:');
      ans
  catch
      sprintf('Error executing function ''%s''\n', func2str(func))
  end
  

The first call to catcherr, shown below, passes a handle to the round function and a valid data argument. This call succeeds and returns the expected answer. The second call passes the same function handle and an improper data type (a MATLAB structure). This time, round fails, causing catcherr to display an error message that includes the failing function name.

• catcherr(@round, 5.432)
  ans =
  Answer is 5
  
  xstruct.value = 5.432;
  catcherr(@round, xstruct)
  Error executing function "round"
  

Types of Function Handles

Converting Function Names to Function Handles