clipper::ResolutionFn_nonlinear Class Reference

2nd order resolution function evaluator More...

#include <resol_fn.h>

Inheritance diagram for clipper::ResolutionFn_nonlinear:

Public Member Functions
	ResolutionFn_nonlinear (const HKL_info &hkl_info, const BasisFn_base &basisfn, const TargetFn_base &targetfn, const std::vector< ftype > &params, const ftype damp=0.0, const bool debug=false)
	constructor: need reflections, basis fn and target fn.
Public Member Functions inherited from clipper::ResolutionFn
	ResolutionFn (const HKL_info &hkl_info, const BasisFn_base &basisfn, const TargetFn_base &targetfn, const std::vector< ftype > &params, const ftype damp=0.0, const bool debug=false)
	constructor: need reflections, basis fn and target fn.
ftype	f (const HKL_info::HKL_reference_index &ih) const
	return the value of the basis function with the current paramters
const std::vector< ftype > &	params () const
	return the values of the parameters
void	debug () const
	print the target, gradient, and curvatures with respect to the params

Additional Inherited Members
Protected Member Functions inherited from clipper::ResolutionFn
void	calc_derivs (const std::vector< ftype > &params, ftype &r, std::vector< ftype > &drdp, Matrix<> &drdp2) const
	calculate derivatives of target wrt params
	ResolutionFn ()
	null constructor
Protected Attributes inherited from clipper::ResolutionFn
const HKL_info *	hkl_info_
	reflection list
const TargetFn_base *	targetfn_
	target function
const BasisFn_base *	basisfn_
	basis function
std::vector< ftype >	params_
	basis function parameters
Cell	cell_
	cell

Detailed Description

2nd order resolution function evaluator

This is an automatic evaluator for arbitrary functions of HKL, most commonly used for evaluating a function of resolution (such a mean F^2 or sigmaa), although more general tasks including local scaling of reflections and anisotropic functions can also be handled. This form is for target functions which approach zero quadratically, e.g. least-squares targets.

Note

This version implements a minimiser which uses both Newton-Raphson and gradient steps depending on the situation. It can be used for non-quadratic targets or non-linear basis functions.

To evaluate a resolution function, this class must be provided with two objects:

• The basis function (and gradients), which describes the value of the function for any reflection given a set of paramters.
• The target function (and derivatives), which is used to determine the values of the basis function parameters.

Constructor & Destructor Documentation

ResolutionFn_nonlinear()

clipper::ResolutionFn_nonlinear::ResolutionFn_nonlinear	(	const HKL_info &	hkl_info,
		const BasisFn_base &	basisfn,
		const TargetFn_base &	targetfn,
		const std::vector< ftype > &	params,
		const ftype	damp = 0.0,
		const bool	debug = false )

constructor: need reflections, basis fn and target fn.

The constructor performs the full minimisation calculation.

Parameters

hkl_info	HKL_info object which provides the reflection list.
basisfn	The basis function used to describe the desired property.
targetfn	The target function to be minimised.
damp_	If > 0.0, shifts are fdamped during early cycles to help convergence with difficult bases/target conbinations

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The documentation for this class was generated from the following files:

• resol_fn.h
• resol_fn.cpp