Gabriele Cosmo
111 lines
3.8 KiB
C++
111 lines
3.8 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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//
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//
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//
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// Helix Explicit Euler: x_1 = x_0 + helix(h)
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// with helix(h) being a helix piece of length h
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// most simple approach for solving linear differential equations.
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// Take the current derivative and add it to the current position.
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//
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// W.Wander <wwc@mit.edu> 12/09/97
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// -------------------------------------------------------------------
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#include "G4HelixExplicitEuler.hh"
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#include "G4PhysicalConstants.hh"
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#include "G4ThreeVector.hh"
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void G4HelixExplicitEuler::Stepper( const G4double yInput[7],
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const G4double*,
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G4double Step,
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G4double yOut[7],
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G4double yErr[])
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{
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//Estimation of the Stepping Angle
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G4ThreeVector Bfld;
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MagFieldEvaluate(yInput, Bfld);
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const G4int nvar = 6 ;
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G4int i;
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G4double yTemp[8], yIn[8] ;
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G4ThreeVector Bfld_midpoint;
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// Saving yInput because yInput and yOut can be aliases for same array
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for(i=0;i<nvar;i++) yIn[i]=yInput[i];
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G4double h = Step * 0.5;
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// Do full step and two half steps
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G4double yTemp2[7];
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AdvanceHelix(yIn, Bfld, h, yTemp2,yTemp);
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MagFieldEvaluate(yTemp2, Bfld_midpoint) ;
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AdvanceHelix(yTemp2, Bfld_midpoint, h, yOut);
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// Error estimation
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for(i=0;i<nvar;i++) {
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yErr[i] = yOut[i] - yTemp[i] ;
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}
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}
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G4double G4HelixExplicitEuler::DistChord() const
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{
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// Implementation : must check whether h/R > 2 pi !!
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// If( h/R < pi) use G4LineSection::DistLine
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// Else DistChord=R_helix
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//
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G4double distChord;
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G4double Ang_curve=GetAngCurve();
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if(Ang_curve<=pi){
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distChord=GetRadHelix()*(1-std::cos(0.5*Ang_curve));
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}
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else
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if(Ang_curve<twopi){
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distChord=GetRadHelix()*(1+std::cos(0.5*(twopi-Ang_curve)));
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}
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else{
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distChord=2.*GetRadHelix();
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}
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return distChord;
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}
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void
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G4HelixExplicitEuler::DumbStepper( const G4double yIn[],
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G4ThreeVector Bfld,
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G4double h,
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G4double yOut[])
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{
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AdvanceHelix(yIn, Bfld, h, yOut);
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}
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