Function data types for parameters and arguments. More...

#include <FunctionTraits.h>

Public Types
typedef T	Type
	Actual template type. More...

typedef T	BaseType
	Template base type. More...

typedef T	NumericType
	Numeric type of template. More...

typedef T	ParamType
	Type for parameters. More...

typedef T	ArgType
	Type for arguments. More...

typedef AutoDiff< T >	DiffType
	Default type for differentiation. More...

Static Public Member Functions
static const T &	getValue (const T &in)
	Get the value. More...

static void	setValue (T &out, const T &val, const uInt, const uInt)
	Set a value (and possible derivative) More...

Detailed Description

template<class T>
class casacore::FunctionTraits< T >

Function data types for parameters and arguments.

Intended use:

Internal

Review Status

Reviewed By:: UNKNOWN
Date Reviewed:: before2004/08/25
Test programs:: t

Prerequisite

Etymology

A trait is a characteristic feature. FunctionTraits defines relationships between the data types of result, parameters and arguments of function objects.

Synopsis

This templated class contains a number of typedefs that describe the relationship between different numeric data types used for the calculation of Function and the function parameter and arguments.

Its main use is to optimize the speed of the calculation of function values and derivatives in the case of AutoDiff use and manual calculation of derivatives, by allowing the data type of the the arguments and/or parameters to be plain numeric in cases where the derivatives wrt these are not needed. To enable this, the following definitions are used for the use of the Function template. Bear in mind that the Function operator is defined as result = f<T>(x; parameters).

Simple numeric type (Double, Complex, etc): result, parameters and arguments: all the one defined templated type.
AutoDiff<T> indicates the calculation (either automatic or with specialized implementations) of the result with a T function value for T arg, and AutoDiff<T> parameters.
AutoDiffA calculate form AutoDiff<T> arguments and parameters (note that either could be simple values with zero derivatives)
AutoDiffX<T> : calculate only with respect to the arguments the derivatives, by using T parameters

The following types are defined:

Type: The template argument
BaseType: One down in the template hierarchy if possible (e.g. Double for AutoDiff<Double>)
NumericType: Ultimate numeric type (e.g. Double for AutoDiff<AutoDiff<Double> >
ParamType: Type used for parameters
ArgType: Type used for arguments
DiffType: The default differentiation type (e.g. AutoDiff<Double> for AutoDiff<Double>)
getValue(): get the value of a simple numeric or of an AutoDiff
setValue(): set the value of a simple numeric or of an AutoDiff

The specializations are done in such a way that higher order derivatives (e.g. AutoDiff<AutoDiff<Double> >) are catered for.

Note that the class names in the following definitions are extended with some individual id (like _PA): do not use them in programming, they are only necessary for the cxx2html interpreter)

This class is implemented as a number of specializations for the following data types.