Data commit

Task/Call-a-function/MATLAB/call-a-function.m

@@ -0,0 +1,49 @@
+    % Calling a function that requires no arguments
+       function a=foo();
+         a=4;
+       end;
+       x = foo();
+    % Calling a function with a fixed number of arguments
+       function foo(a,b,c);
+         %% function definition;
+       end;
+       foo(x,y,z);
+    % Calling a function with optional arguments
+       function foo(a,b,c);
+	if nargin<2, b=0; end;
+	if nargin<3, c=0; end;
+         %% function definition;
+       end;
+       foo(x,y);
+    % Calling a function with a variable number of arguments
+       function foo(varargin);
+	  for k=1:length(varargin)
+            arg{k} = varargin{k};	
+       end;
+       foo(x,y);
+    % Calling a function with named arguments
+	%% does not apply
+    % Using a function in statement context
+	%% does not apply
+    % Using a function in first-class context within an expression
+    % Obtaining the return value of a function
+       function [a,b]=foo();
+         a=4;
+         b='result string';
+       end;
+       [x,y] = foo();
+    % Distinguishing built-in functions and user-defined functions
+	fun = 'foo';	
+	if (exist(fun,'builtin'))
+ 		printf('function %s is a builtin\n');
+        elseif (exist(fun,'file'))
+ 		printf('function %s is user-defined\n');
+        elseif (exist(fun,'var'))
+ 		printf('function %s is a variable\n');
+        else
+ 		printf('%s is not a function or variable.\n');
+        end
+    % Distinguishing subroutines and functions
+        % there are only scripts and functions, any function declaration starts with the keyword function, otherwise it is a script that runs in the workspace
+    % Stating whether arguments are passed by value or by reference
+      % arguments are passed by value, however Matlab has delayed evaluation, such that a copy of large data structures are done only when an element is written to.