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geant4/source/global/HEPNumerics/include/G4PolynomialSolver.hh
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//
// ********************************************************************
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// * *
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//
//
// $Id: G4PolynomialSolver.hh 67970 2013-03-13 10:10:06Z gcosmo $
//
// class G4PolynomialSolver
//
// Class description:
//
// G4PolynomialSolver allows the user to solve a polynomial equation
// with a great precision. This is used by Implicit Equation solver.
//
// The Bezier clipping method is used to solve the polynomial.
//
// How to use it:
// Create a class that is the function to be solved.
// This class could have internal parameters to allow to change
// the equation to be solved without recreating a new one.
//
// Define a Polynomial solver, example:
// G4PolynomialSolver<MyFunctionClass,G4double(MyFunctionClass::*)(G4double)>
// PolySolver (&MyFunction,
// &MyFunctionClass::Function,
// &MyFunctionClass::Derivative,
// precision);
//
// The precision is relative to the function to solve.
//
// In MyFunctionClass, provide the function to solve and its derivative:
// Example of function to provide :
//
// x,y,z,dx,dy,dz,Rmin,Rmax are internal variables of MyFunctionClass
//
// G4double MyFunctionClass::Function(G4double value)
// {
// G4double Lx,Ly,Lz;
// G4double result;
//
// Lx = x + value*dx;
// Ly = y + value*dy;
// Lz = z + value*dz;
//
// result = TorusEquation(Lx,Ly,Lz,Rmax,Rmin);
//
// return result ;
// }
//
// G4double MyFunctionClass::Derivative(G4double value)
// {
// G4double Lx,Ly,Lz;
// G4double result;
//
// Lx = x + value*dx;
// Ly = y + value*dy;
// Lz = z + value*dz;
//
// result = dx*TorusDerivativeX(Lx,Ly,Lz,Rmax,Rmin);
// result += dy*TorusDerivativeY(Lx,Ly,Lz,Rmax,Rmin);
// result += dz*TorusDerivativeZ(Lx,Ly,Lz,Rmax,Rmin);
//
// return result;
// }
//
// Then to have a root inside an interval [IntervalMin,IntervalMax] do the
// following:
//
// MyRoot = PolySolver.solve(IntervalMin,IntervalMax);
//
// History:
//
// - 19.12.00 E.Medernach, First implementation
//
#ifndef G4POL_SOLVER_HH
#define G4POL_SOLVER_HH
#include "globals.hh"
template <class T, class F>
class G4PolynomialSolver
{
public: // with description
G4PolynomialSolver(T* typeF, F func, F deriv, G4double precision);
~G4PolynomialSolver();
G4double solve (G4double IntervalMin, G4double IntervalMax);
private:
G4double Newton (G4double IntervalMin, G4double IntervalMax);
//General Newton method with Bezier Clipping
// Works for polynomial of order less or equal than 4.
// But could be changed to work for polynomial of any order providing
// that we find the bezier control points.
G4int BezierClipping(G4double *IntervalMin, G4double *IntervalMax);
// This is just one iteration of Bezier Clipping
T* FunctionClass ;
F Function ;
F Derivative ;
G4double Precision;
};
#include "G4PolynomialSolver.icc"
#endif