Info Catalog octave: Function Handles octave: Function Handles Anonymous Functions Inline Functions octave: Inline Functions

octave: Anonymous Functions

 
 11.11.2 Anonymous Functions
 ---------------------------
 
 Anonymous functions are defined using the syntax
 
      @(ARGUMENT-LIST) EXPRESSION
 
 Any variables that are not found in the argument list are inherited from
 the enclosing scope.  Anonymous functions are useful for creating simple
 unnamed functions from expressions or for wrapping calls to other
 functions to adapt them for use by functions like ‘quad’.  For example,
 
      f = @(x) x.^2;
      quad (f, 0, 10)
          ⇒ 333.33
 
 creates a simple unnamed function from the expression ‘x.^2’ and passes
 it to ‘quad’,
 
      quad (@(x) sin (x), 0, pi)
          ⇒ 2
 
 wraps another function, and
 
      a = 1;
      b = 2;
      quad (@(x) betainc (x, a, b), 0, 0.4)
          ⇒ 0.13867
 
 adapts a function with several parameters to the form required by
 ‘quad’.  In this example, the values of A and B that are passed to
 ‘betainc’ are inherited from the current environment.
 
    Note that for performance reasons it is better to use handles to
 existing Octave functions, rather than to define anonymous functions
 which wrap an existing function.  The integration of ‘sin (x)’ is 5X
 faster if the code is written as
 
      quad (@sin, 0, pi)
 
 rather than using the anonymous function ‘@(x) sin (x)’.  There are many
 operators which have functional equivalents that may be better choices
 than an anonymous function.  Instead of writing
 
      f = @(x, y) x + y
 
 this should be coded as
 
      f = @plus
 
    Operator Overloading, for a list of operators which also have
 a functional form.
 

Info Catalog octave: Function Handles octave: Function Handles Anonymous Functions Inline Functions octave: Inline Functions