Gabriele Cosmo
147 lines
5.4 KiB
C++
147 lines
5.4 KiB
C++
// This code implementation is the intellectual property of
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// the GEANT4 collaboration.
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//
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// By copying, distributing or modifying the Program (or any work
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// based on the Program) you indicate your acceptance of this statement,
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// and all its terms.
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//
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// $Id: G4DataInterpolation.hh,v 1.3 2000/11/20 17:26:41 gcosmo Exp $
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// GEANT4 tag $Name: geant4-03-00 $
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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 extrapolations.
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// The methods based mainly on recommendations given in the book : An introduction to
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// NUMERICAL METHODS IN C++, B.H. Flowers, Claredon Press, Oxford, 1995
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//
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// ------------------------------ Data members: ---------------------------------
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//
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// fArgument and fFunction - pointers to data table to be interpolated
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// for y[i] and x[i] respectively
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// fNumber - the corresponding table size
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// ......
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// G4DataInterpolation( G4double pX[], G4double pY[], G4int number )
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//
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// Constructor for initializing of fArgument, fFunction and fNumber data members:
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// ......
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// G4DataInterpolation( G4double pX[], G4double pY[], G4int number,
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// G4double pFirstDerStart, G4double pFirstDerFinish )
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//
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// Constructor for cubic spline interpolation. It creates the array
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// fSecondDerivative[0,...fNumber-1] which is used in this interpolation by
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// the function:
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// ....
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// ~G4DataInterpolation()
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//
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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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//
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// ------------------------------ Methods: ----------------------------------------
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//
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// G4double PolynomInterpolation(G4double pX, G4double& deltaY ) const
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//
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// This function returns the value P(pX), where P(x) is polynom of fNumber-1 degree
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// such that P(fArgument[i]) = fFunction[i], for i = 0, ..., fNumber-1 .
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// ........
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// void PolIntCoefficient( G4double cof[]) const
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//
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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. The coefficients don't provide
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// usually (fNumber>10) better accuracy for polynom interpolation, as compared with
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// PolynomInterpolation function. They could be used instead for derivate
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// calculations and some other applications.
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// .........
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// G4double RationalPolInterpolation(G4double pX, G4double& deltaY ) const
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//
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// The function returns diagonal rational function (Bulirsch and Stoer algorithm
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// 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 with
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// polynomial interpolation
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// ................
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// G4double CubicSplineInterpolation(G4double pX) const
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//
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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, must be
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// called before. The function works optimal, if sequential calls are in random
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// values of pX.
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// ..................
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// G4double FastCubicSpline(G4double pX, G4int index) const
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//
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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 of
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// known from external analysis values of index.
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// .........
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// G4int LocateArgument(G4double pX) const
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//
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// Given argument pX, returns index k, so that pX bracketed by fArgument[k] and
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// fArgument[k+1]
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// ......................
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// void CorrelatedSearch( G4double pX, G4int& index ) const
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//
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// Given a value pX, returns a value 'index' such that pX is between fArgument[index]
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// and fArgument[index+1]. fArgument MUST BE MONOTONIC, either increasing or
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// decreasing. If index = -1 or fNumber, this indicates that pX is out of range.
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// The value index on input is taken as the initial approximation for index on
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// output.
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// --------------------------------- History: --------------------------------------
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//
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// 3.4.97 V.Grichine (Vladimir.Grichine@cern.ch)
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//
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#ifndef G4DATAINTERPOLATION_HH
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#define G4DATAINTERPOLATION_HH
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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[],
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G4double pY[],
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G4int number );
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// Constructor for cubic spline interpolation. It creates fSecond Deivative array
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// as well as fArgument and fFunction
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G4DataInterpolation( G4double pX[],
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G4double pY[],
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G4int number,
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G4double pFirstDerStart,
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G4double pFirstDerFinish ) ;
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~G4DataInterpolation() ;
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G4double PolynomInterpolation( G4double pX,
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G4double& deltaY ) const ;
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void PolIntCoefficient( G4double cof[]) const ;
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G4double RationalPolInterpolation( G4double pX,
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G4double& deltaY ) const ;
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G4double CubicSplineInterpolation( G4double pX ) const ;
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G4double FastCubicSpline( G4double pX,
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G4int index ) const ;
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G4int LocateArgument( G4double pX ) const ;
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void CorrelatedSearch( G4double pX,
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G4int& index ) const ;
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private:
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G4DataInterpolation(const G4DataInterpolation&);
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G4DataInterpolation& operator=(const G4DataInterpolation&);
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private:
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G4double* fArgument ;
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G4double* fFunction ;
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G4double* fSecondDerivative ;
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G4int fNumber ;
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} ;
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#endif
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