Gabriele Cosmo
112 lines
5.2 KiB
C++
112 lines
5.2 KiB
C++
//
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// ********************************************************************
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// * License and Disclaimer *
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// * *
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// * The Geant4 software is copyright of the Copyright Holders of *
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// * the Geant4 Collaboration. It is provided under the terms and *
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// * conditions of the Geant4 Software License, included in the file *
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// * LICENSE and available at http://cern.ch/geant4/license . These *
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// * include a list of copyright holders. *
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// * *
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// * Neither the authors of this software system, nor their employing *
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// * institutes,nor the agencies providing financial support for this *
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// * work make any representation or warranty, express or implied, *
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// * regarding this software system or assume any liability for its *
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// * use. Please see the license in the file LICENSE and URL above *
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// * for the full disclaimer and the limitation of liability. *
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// * *
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// * This code implementation is the result of the scientific and *
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// * technical work of the GEANT4 collaboration. *
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// * By using, copying, modifying or distributing the software (or *
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// * any work based on the software) you agree to acknowledge its *
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// * use in resulting scientific publications, and indicate your *
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// * acceptance of all terms of the Geant4 Software license. *
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// ********************************************************************
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//
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// G4DataInterpolation
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//
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// Class description:
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//
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// The class consists of some methods for data interpolations and
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// extrapolations. The methods based mainly on recommendations given in the
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// book: An introduction to NUMERICAL METHODS IN C++, B.H. Flowers,
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// Claredon Press, Oxford, 1995.
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// Author: V.Grichine, 03.04.1997
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// --------------------------------------------------------------------
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#ifndef G4DATAINTERPOLATION_HH
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#define G4DATAINTERPOLATION_HH 1
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#include "globals.hh"
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class G4DataInterpolation
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{
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public:
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G4DataInterpolation(G4double pX[], G4double pY[], G4int number);
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// Constructor for initializing data members.
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G4DataInterpolation(G4double pX[], G4double pY[], G4int number,
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G4double pFirstDerStart, G4double pFirstDerFinish);
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// Constructor for cubic spline interpolation. It creates fSecond Deivative
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// array as well as fArgument and fFunction.
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~G4DataInterpolation();
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// Destructor deletes dynamically created arrays for data members: fArgument,
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// fFunction and fSecondDerivative, all have dimension of fNumber.
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G4DataInterpolation(const G4DataInterpolation&) = delete;
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G4DataInterpolation& operator=(const G4DataInterpolation&) = delete;
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// Copy constructor and assignement operator not allowed.
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G4double PolynomInterpolation(G4double pX, G4double& deltaY) const;
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// This function returns the value P(pX), where P(x) is polynom of fNumber-1
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// degree such that P(fArgument[i]) = fFunction[i], for i = 0, ..., fNumber-1.
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void PolIntCoefficient(G4double cof[]) const;
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// Given arrays fArgument[0,..,fNumber-1] and fFunction[0,..,fNumber-1], this
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// function calculates an array of coefficients.
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// The coefficients don't provide usually (fNumber>10) better accuracy for
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// polynom interpolation, as compared with PolynomInterpolation() function.
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// They could be used instead for derivate calculations and some other
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// applications.
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G4double RationalPolInterpolation(G4double pX, G4double& deltaY) const;
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// The function returns diagonal rational function (Bulirsch and Stoer
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// algorithm of Neville type) Pn(x)/Qm(x) where P and Q are polynoms.
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// Tests showed the method is not stable and hasn't advantage if compared
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// with polynomial interpolation.
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G4double CubicSplineInterpolation(G4double pX) const;
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// Cubic spline interpolation in point pX for function given by the table:
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// fArgument, fFunction. The constructor, which creates fSecondDerivative,
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// must be called before. The function works optimal, if sequential calls
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// are in random values of pX.
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G4double FastCubicSpline(G4double pX, G4int index) const;
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// Return cubic spline interpolation in the point pX which is located between
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// fArgument[index] and fArgument[index+1]. It is usually called in sequence
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// of known from external analysis values of index.
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G4int LocateArgument(G4double pX) const;
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// Given argument pX, returns index k, so that pX bracketed by fArgument[k]
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// and fArgument[k+1].
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void CorrelatedSearch(G4double pX, G4int& index) const;
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// Given a value pX, returns a value 'index' such that pX is between
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// fArgument[index] and fArgument[index+1]. fArgument MUST BE MONOTONIC,
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// either increasing or decreasing. If index = -1 or fNumber, this indicates
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// that pX is out of range. The value index on input is taken as the initial
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// approximation for index on output.
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private:
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// pointers to data table to be interpolated for y[i] and x[i] respectively
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G4double* fArgument = nullptr;
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G4double* fFunction = nullptr;
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G4double* fSecondDerivative = nullptr;
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G4int fNumber = 0; // the corresponding table size
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};
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#endif
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