lines 8-131 of file: cpp/include/cmpad/fun_obj.hpp

{xrst_begin cpp_fun_obj}
{xrst_spell
   vec
   resize
   th
   typedef
   typename
}

The New Abstract Class for a C++ Function Object
################################################

Syntax
******
| |tab| ``# include <cmpad/fun_obj.hpp``
| |tab| ``cmpad::fun_obj`` < *Vector* > *fun*
| |tab| ``cmpad::fun_obj`` < *Vector* > :: ``scalar_type``
| |tab| *fun* . ``setup`` ( *option* )
| |tab| *fun* . ``domain`` ( )
| |tab| *fun* . ``range`` ( )
| |tab| *y* = *fun* ( *x* )

Source Code
***********
{xrst_literal
   // BEGIN C++
   // END C++
}

vector_type
***********
A derived class must define *vector_type* to be the same as *Vector* .
This is intended for use when derived class type
is passed as a template parameter.

scalar_type
***********
A derived class must also define *scalar_type* to be the type
of the elements of *vec* ; i.e.,
{xrst_code cpp}
   typedef typename Vector::value_type scalar_type
{xrst_code}
If *i* is a positive integer constant and
*s*, *t* are *scalar_type* objects,
the following operations must be defined:

#. The constructors: *scalar_type* (i),  *scalar_type* (s) .
#. This binary operations:
   *s* + *t* ,
   *s* - *t* ,
   *s* * *t* ,
   *s* / *t* .

Vector
******
The fun_obj *Vector* class must support the following
where *vec* is a *Vector* object:

Vector::value_type
==================
is the type of the elements of *vec* .

vec.resize(n)
=============
resize the vector to have size *n* where *n* is a ``size_t`` object.

vec.size()
==========
returns a ``size_t`` that is the current size of the vector.

vec[i]
======
returns a reference, or constant reference, to the i-th element of *vec*
where *i* is an ``size_t`` .

fun
***
This is the function object.
The corresponding function call,
*y* = *fun* ( *x* ),
computes *y* as a function of *x* .



setup
*****
The function object is initialized using the ``setup`` syntax.
The ``setup`` can (and should) do calculations that do not depend on *x*
(to make the evaluation of the function call faster).

option
******
This interface does not place any restrictions on the content of *option* .

domain
******
The return value is the dimension of the domain space for
this function; i.e. the size of *x*.
It likely depends on the value of *option*.

range
*****
The return value is the dimension of the range space for
this function; i.e. the size of *y*.
It likely depends on the value of *option*.

x
*
This *Vector* has size *n* and
is the point at which the function is evaluated.

y
*
This *Vector* has size *m* and
is the function value corresponding to *x*.

{xrst_toc_hidden
   cpp/xam/fun_obj.cpp
}
Example
*******
:ref:`xam_fun_obj.cpp-name` is an example and test that uses this function.

{xrst_end cpp_fun_obj}