USGS Astrogeology Isis API

This is a base class for generating "generic" equations for the Isis least squares fitting algorithm (IsisLSQ). It allows the programmer to set up equations in the form of:

where C1-CN are coefficients and T1-TN are terms. Note that terms can be comprised of multiple variables and/or functions. For example,

By deriving different functions off of this base class this allows the least squares class to be generalized.

Definition at line 59 of file BasisFunction.h.


Public Member Functions
	BasisFunction (const std::string &name, int numVars, int numCoefs)
	Creates a BasisFunction object.
virtual	~BasisFunction ()
	Destroys the BasisFunction object.
void	SetCoefficients (const std::vector< double > &coefs)
	Set the coefficients for the equation.
double	Evaluate (const std::vector< double > &vars)
	Compute the equation using the input variables.
virtual void	Expand (const std::vector< double > &vars)
	This is the function you should replace depending on your needs.
int	Coefficients () const
	Returns the number of coefficients for the equation.
int	Variables () const
	Returns the number of variables in the equation.
std::string	Name () const
	Returns the name of the equation.
double	Term (int c) const
	Returns the cth term.
double	Coefficient (int i) const
	Returns the ith coefficient.
Protected Attributes
std::string	p_name
	The name of the equation. Call it by using Name().
int	p_numVars
	The number of variables in the equation. Call it by using Variables().
int	p_numCoefs
	The number of coefficients in the equation.
std::vector< double >	p_coefs
	A vector of the coefficients in the equation.
std::vector< double >	p_terms
	A vector of the terms in the equation.

Constructor & Destructor Documentation

Isis::BasisFunction::BasisFunction	(	const std::string &	name,
		int	numVars,
		int	numCoefs
	)

Creates a BasisFunction object.

Parameters:

name

Name of the BasisFunction. For example, "affine".

numVars

Number of variables in the equation. For example:

$x = C1 + C2*y + C3*z$

has two variables: y and z.

numCoefs

Number of coefficients in the equation. For example:

$x = C1 + C2*y + C3*z$

has three coefficients: C1, C2 & C3.

Definition at line 44 of file BasisFunction.cpp.

References p_name, p_numCoefs, and p_numVars.

virtual Isis::BasisFunction::~BasisFunction ( ) [inline, virtual]

Destroys the BasisFunction object.

Definition at line 63 of file BasisFunction.h.

Member Function Documentation

double Isis::BasisFunction::Coefficient ( int i ) const [inline]

Returns the ith coefficient.

Parameters:

The index for the desired coefficient.

Returns:: The ith coefficient

Definition at line 109 of file BasisFunction.h.

Referenced by Isis::PolynomialUnivariate::DerivativeVar(), Isis::SurfaceModel::MinMax(), Isis::AutoReg::ModelSurface(), Isis::SpicePosition::ReloadCache(), Isis::SpicePosition::SetPolynomial(), Isis::OverlapNormalization::Solve(), Isis::Affine::Solve(), and Isis::BundleAdjust::Update().

int Isis::BasisFunction::Coefficients ( ) const [inline]

Returns the number of coefficients for the equation.

Returns:: The number of coefficients.

Definition at line 74 of file BasisFunction.h.

References p_numCoefs.

Referenced by Isis::PolynomialUnivariate::DerivativeCoef(), Isis::PolynomialUnivariate::DerivativeVar(), Isis::SpicePosition::SetPolynomial(), Isis::OverlapNormalization::Solve(), Isis::LeastSquares::SolveQRD(), and Isis::LeastSquares::SolveSVD().

double Isis::BasisFunction::Evaluate ( const std::vector< double > & vars )

Compute the equation using the input variables.

Parameters:

vars

A vector of double values to use for the equation. After setting the coefficients, this can be invoked many times to compute output values given input values.

Returns:: The output value.

Definition at line 73 of file BasisFunction.cpp.

References _FILEINFO_, Expand(), Isis::iException::Message(), p_coefs, p_numCoefs, p_numVars, and p_terms.

Referenced by Isis::LeastSquares::Evaluate(), Isis::SpicePosition::ReloadCache(), Isis::LeastSquares::SolveQRD(), Isis::LeastSquares::SolveSparse(), and Isis::LeastSquares::SolveSVD().

void Isis::BasisFunction::Expand ( const std::vector< double > & vars ) [virtual]

This is the function you should replace depending on your needs.

It will expand the variables into the terms of the equation. For example,

$x = C1 + C2*y + C3*z + C4*y*z$

must be expanded into the p_terms vector as (1.0, y, z, y*z). Note that the term expansion is not limited, you can use cos, sin, sqrt, abs, etc. This virtual method is automatically invoked by the Evaluate method. We provide a default expansion of p_terms = vars, just a linear combination of the variables.

Parameters:

vars

A vector of double values to use for the expansion.

Reimplemented in Isis::Parabola, Isis::PolynomialBivariate, and Isis::PolynomialUnivariate.

Definition at line 108 of file BasisFunction.cpp.

References p_terms.

Referenced by Evaluate(), Isis::LeastSquares::FillSparseA(), Isis::LeastSquares::SolveQRD(), and Isis::LeastSquares::SolveSVD().

std::string Isis::BasisFunction::Name ( ) const [inline]

Returns the name of the equation.