Gabriele Cosmo
300 lines
9.6 KiB
C++
300 lines
9.6 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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// class G4HelixMixedStepper
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//
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// Class description:
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//
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// G4HelixMixedStepper split the Method used for Integration in two:
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//
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// If Stepping Angle ( h / R_curve) < pi/3
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// use Stepper for small step(ClassicalRK4 by default)
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// Else use HelixExplicitEuler Stepper
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//
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// History:
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// Derived from ExactHelicalStepper 18/05/07
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//
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// -------------------------------------------------------------------------
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#include "G4HelixMixedStepper.hh"
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#include "G4PhysicalConstants.hh"
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#include "G4ClassicalRK4.hh"
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#include "G4CashKarpRKF45.hh"
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#include "G4SimpleRunge.hh"
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#include "G4HelixImplicitEuler.hh"
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#include "G4HelixExplicitEuler.hh"
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#include "G4HelixSimpleRunge.hh"
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#include "G4ExactHelixStepper.hh"
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#include "G4ExplicitEuler.hh"
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#include "G4ImplicitEuler.hh"
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#include "G4SimpleHeum.hh"
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#include "G4RKG3_Stepper.hh"
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#include "G4NystromRK4.hh"
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// Additional potential stepper
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#include "G4DormandPrince745.hh"
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#include "G4BogackiShampine23.hh"
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#include "G4BogackiShampine45.hh"
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#include "G4TsitourasRK45.hh"
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#include "G4ThreeVector.hh"
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#include "G4LineSection.hh"
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G4HelixMixedStepper::
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G4HelixMixedStepper(G4Mag_EqRhs *EqRhs, G4int stepperNumber,
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G4double angleThreshold)
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: G4MagHelicalStepper(EqRhs), fNumCallsRK4(0), fNumCallsHelix(0)
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{
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SetVerbose(1);
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if( angleThreshold < 0.0 ){
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fAngle_threshold= 0.33*pi;
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}else{
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fAngle_threshold= angleThreshold;
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}
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if(stepperNumber<0)
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stepperNumber=4; // Default is RK4 (original)
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// stepperNumber=745; // Default is DormandPrince745 (ie DoPri5)
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// stepperNumber=8; // Default is CashKarp
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fStepperNumber = stepperNumber; // Store the choice
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fRK4Stepper = SetupStepper(EqRhs, fStepperNumber);
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}
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G4HelixMixedStepper::~G4HelixMixedStepper()
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{
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delete(fRK4Stepper);
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if (fVerbose>0){ PrintCalls();};
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}
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void G4HelixMixedStepper::Stepper( const G4double yInput[7],
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const G4double dydx[7],
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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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G4double Bmag = Bfld.mag();
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const G4double *pIn = yInput+3;
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G4ThreeVector initVelocity= G4ThreeVector( pIn[0], pIn[1], pIn[2]);
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G4double velocityVal = initVelocity.mag();
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G4double R_1;
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G4double Ang_curve;
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R_1=std::abs(GetInverseCurve(velocityVal,Bmag));
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Ang_curve=R_1*Step;
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SetAngCurve(Ang_curve);
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SetCurve(std::abs(1/R_1));
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if(Ang_curve< fAngle_threshold){
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fNumCallsRK4++;
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fRK4Stepper->Stepper(yInput,dydx,Step,yOut,yErr);
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}
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else
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{
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fNumCallsHelix++;
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const G4int nvar = 6 ;
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const G4int nvarMax = 8 ;
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G4int i;
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G4double yTemp[nvarMax], yIn[nvarMax], yTemp2[nvarMax];
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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 halfS = Step * 0.5;
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// 1. Do first half step and full step
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AdvanceHelix(yIn, Bfld, halfS, yTemp, yTemp2); // yTemp2 for s=2*h (halfS)
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//**********
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MagFieldEvaluate(yTemp, Bfld_midpoint) ;
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// 2. Do second half step - with revised field
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// NOTE: Could avoid this call if 'Bfld_midpoint == Bfld'
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// or diff 'almost' zero
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AdvanceHelix(yTemp, Bfld_midpoint, halfS, yOut);
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// Not requesting y at s=2*h (halfS)
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//**********
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// 3. Estimate the integration error
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// should be (nearly) zero if Bfield= constant
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for(i=0;i<nvar;i++) {
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yErr[i] = yOut[i] - yTemp2[i] ;
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}
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}
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}
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void
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G4HelixMixedStepper::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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G4double G4HelixMixedStepper::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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{
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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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}
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return distChord;
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}
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// ---------------------------------------------------------------------------
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void G4HelixMixedStepper::PrintCalls()
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{
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G4cout << "In HelixMixedStepper::Number of calls to smallStepStepper = "
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<< fNumCallsRK4
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<< " and Number of calls to Helix = " << fNumCallsHelix << G4endl;
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}
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G4MagIntegratorStepper*
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G4HelixMixedStepper::SetupStepper(G4Mag_EqRhs* pE, G4int StepperNumber)
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{
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G4MagIntegratorStepper* pStepper;
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if (fVerbose>0) G4cout << " G4HelixMixedStepper: ";
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switch ( StepperNumber )
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{
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// Robust, classic method
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case 4:
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pStepper = new G4ClassicalRK4( pE );
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if (fVerbose>0) G4cout << "G4ClassicalRK4";
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break;
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// Steppers with embedded estimation of error
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case 8:
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pStepper = new G4CashKarpRKF45( pE );
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if (fVerbose>0) G4cout << "G4CashKarpRKF45";
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break;
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case 13:
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pStepper = new G4NystromRK4( pE );
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if (fVerbose>0) G4cout << "G4NystromRK4";
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break;
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// Lowest order RK Stepper - experimental
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case 1:
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pStepper = new G4ImplicitEuler( pE );
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if (fVerbose>0) G4cout << "G4ImplicitEuler";
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break;
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// Lower order RK Steppers - ok overall, good for uneven fields
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case 2:
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pStepper = new G4SimpleRunge( pE );
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if (fVerbose>0) G4cout << "G4SimpleRunge";
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break;
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case 3:
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pStepper = new G4SimpleHeum( pE );
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if (fVerbose>0) G4cout << "G4SimpleHeum";
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break;
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case 23:
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pStepper = new G4BogackiShampine23( pE );
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if (fVerbose>0) G4cout << "G4BogackiShampine23";
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break;
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// Higher order RK Steppers
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// for smoother fields and high accuracy requirements
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case 45:
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pStepper = new G4BogackiShampine45( pE );
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if (fVerbose>0) G4cout << "G4BogackiShampine45";
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break;
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case 145:
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pStepper = new G4TsitourasRK45( pE );
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if (fVerbose>0) G4cout << "G4TsitourasRK45";
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break;
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case 745:
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pStepper = new G4DormandPrince745( pE );
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if (fVerbose>0) G4cout << "G4DormandPrince745";
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break;
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// Helical Steppers
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case 6:
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pStepper = new G4HelixImplicitEuler( pE );
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if (fVerbose>0) G4cout << "G4HelixImplicitEuler";
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break;
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case 7:
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pStepper = new G4HelixSimpleRunge( pE );
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if (fVerbose>0) G4cout << "G4HelixSimpleRunge";
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break;
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case 5:
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pStepper = new G4HelixExplicitEuler( pE );
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if (fVerbose>0) G4cout << "G4HelixExplicitEuler";
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break; // Since Helix Explicit is used for long steps,
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// this is useful only to measure overhead.
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// Exact Helix - likely good only for cases of
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// i) uniform field (potentially over small distances)
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// ii) segmented uniform field (maybe)
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case 9:
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pStepper = new G4ExactHelixStepper( pE );
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if (fVerbose>0) G4cout << "G4ExactHelixStepper";
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break;
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case 10:
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pStepper = new G4RKG3_Stepper( pE );
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if (fVerbose>0) G4cout << "G4RKG3_Stepper";
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break;
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// Low Order Steppers - not good except for very weak fields
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case 11:
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pStepper = new G4ExplicitEuler( pE );
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if (fVerbose>0) G4cout << "G4ExplicitEuler";
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break;
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case 12:
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pStepper = new G4ImplicitEuler( pE );
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if (fVerbose>0) G4cout << "G4ImplicitEuler";
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break;
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case 0:
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case -1:
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default:
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pStepper = new G4ClassicalRK4( pE );
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if (fVerbose>0) G4cout << "G4ClassicalRK4 (Default)";
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break;
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}
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if(fVerbose>0)
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G4cout << " chosen as stepper for small steps in G4HelixMixedStepper."
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<< G4endl;
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return pStepper;
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}
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