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G4HelixExplicitEuler.cc
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the newest version in sPHENIX GitHub for file G4HelixExplicitEuler.cc
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//
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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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// G4HelixExplicitEuler implementation
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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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// Author: W.Wander <wwc@mit.edu>, 12.09.1997
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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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G4HelixExplicitEuler::G4HelixExplicitEuler
(
G4Mag_EqRhs
* EqRhs)
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:
G4MagHelicalStepper
(EqRhs)
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{
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}
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G4HelixExplicitEuler::~G4HelixExplicitEuler
()
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{
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}
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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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//
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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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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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//
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for
(
G4int
i=0; i<nvar; ++i)
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{
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yIn[i] = yInput[i];
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}
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G4double
h
= Step * 0.5;
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// Do full step and two half steps
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//
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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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SetAngCurve
(
GetAngCurve
() * 2);
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// Error estimation
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//
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for
(
G4int
i=0; i<nvar; ++i)
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{
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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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{
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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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void
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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}
geant4
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geant4-10.6-release
source
geometry
magneticfield
src
G4HelixExplicitEuler.cc
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Jin Huang
. updated:
Wed Jun 29 2022 17:25:16
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