Gabriele Cosmo
127 lines
4.1 KiB
C++
127 lines
4.1 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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// G4ExactHelixStepper implementation
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//
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// Author: J.Apostolakis, 28.01.2005.
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// Implementation adapted from ExplicitEuler by W.Wander
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// -------------------------------------------------------------------
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#include "G4ExactHelixStepper.hh"
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#include "G4PhysicalConstants.hh"
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#include "G4ThreeVector.hh"
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#include "G4LineSection.hh"
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G4ExactHelixStepper::G4ExactHelixStepper(G4Mag_EqRhs* EqRhs)
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: G4MagHelicalStepper(EqRhs),
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fBfieldValue(DBL_MAX, DBL_MAX, DBL_MAX)
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{
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}
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G4ExactHelixStepper::~G4ExactHelixStepper()
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{
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}
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// ---------------------------------------------------------------------------
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void
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G4ExactHelixStepper::Stepper( const G4double yInput[],
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const G4double*,
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G4double hstep,
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G4double yOut[],
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G4double yErr[] )
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{
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const G4int nvar = 6;
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G4int i;
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G4ThreeVector Bfld_value;
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MagFieldEvaluate(yInput, Bfld_value);
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AdvanceHelix(yInput, Bfld_value, hstep, yOut);
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// We are assuming a constant field: helix is exact
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//
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for(i=0; i<nvar; ++i)
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{
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yErr[i] = 0.0 ;
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}
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fBfieldValue = Bfld_value;
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}
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// ---------------------------------------------------------------------------
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void
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G4ExactHelixStepper::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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// Assuming a constant field: solution is a helix
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AdvanceHelix(yIn, Bfld, h, yOut);
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G4Exception("G4ExactHelixStepper::DumbStepper",
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"GeomField0002", FatalException,
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"Should not be called. Stepper must do all the work." );
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}
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// ---------------------------------------------------------------------------
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G4double
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G4ExactHelixStepper::DistChord() const
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{
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// Implementation : must check whether h/R > pi !!
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// If( h/R < pi) DistChord=h/2*std::tan(Ang_curve/4)
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// Else DistChord=R_helix
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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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{
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distChord=GetRadHelix()*(1-std::cos(0.5*Ang_curve));
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}
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else if(Ang_curve<twopi)
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{
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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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{
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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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// ---------------------------------------------------------------------------
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G4int
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G4ExactHelixStepper::IntegratorOrder() const
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{
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return 1;
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}
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