A first attempt at doing so has no effect: addtest2.m Suppose, however, we want to replace the value of the first argument by the computed sum. Here is an example of a trivial function that adds its first argument to twice its second argument: addtest.m The flip side of this fact is that functions are harder to debug than scripts without using the keyboard function, because the intermediate calculations used in the function are not available once the function exits. That means that a function can freely define and use variables without unintentionally using a variable name reserved elsewhere. That means that variables defined or modified inside a function do not affect the scope of the caller. An example of using helper functions is included in the examples.Īnother important feature of functions, as opposed to, say scripts, is that they have their own scope. Furthermore the names of these helper functions are determined by their declaration and not by the name of the. These are functions that can only be called by other functions in the same. Additional functions that appear after the first function are known as helper functions or local functions. Note that this is only true for the first function that appears in a. So, for example, if the file is named foo.m, but the declaration uses bar for the name of the function, in FreeMat, it will still appear as function foo. Note that the name of the file (and not the function name fname used in the declaration) is how the function appears in FreeMat. The function name fname can be any legal FreeMat identifier. See help varargin and varargout for more details. Similarly, the function can create a cell array named varargout for variable length output lists. Inside the function, varargin is a cell-array that contains all arguments passed to the function that have not already been accounted for. In these cases, the last argument to the parameter list is the special argument varargin. In some circumstances, it is necessary to have functions that take a variable number of arguments, or that return a variable number of results. See help for nargin and nargout for more details. To assist in deciphering the exact parameters that were passed, FreeMat also defines two variables inside the function context: nargin and nargout, which provide the number of input and output parameters of the caller, respectively. Also, when keywords (see help keywords) are used, an arbitrary subset of the parameters may be unspecified. Also, FreeMat works like C in that the caller does not have to supply the full list of arguments. In which case in_2 is passed by reference and not by value. Arguments can be passed by reference by prepending an ampersand & before the name of the input, e.g. Note that by default, FreeMat passes arguments by value, meaning that if we modify the contents of in_i inside the function, it has no effect on any variables used by the caller. Also, the function must assign values for out_i to pass values to the caller. In the body of the function in_i are initialized with the values passed when the function is called. Likewise, a function with no arguments can eliminate the list of parameters in the declaration: function = fnameįunctions that return only a single value can omit the brackets function out_1 = fname(in_1.,in_N) Note that functions that have no return arguments can omit the return argument list (of out_i) and the equals sign: function fname(in_1.,in_N) For functions with a fixed number of input or output parameters, the syntax is somewhat simpler: function = fname(in_1.,in_N) Where out_i are the output parameters, in_i are the input parameters, and varargout and varargin are special keywords used for functions that have variable inputs or outputs. The most general syntax for a function declaration is the following: function = fname(in_1.,in_N,varargin) There are several forms for function declarations in FreeMat.
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