[831] | 1 | // |
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| 2 | // ******************************************************************** |
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| 3 | // * License and Disclaimer * |
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| 4 | // * * |
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| 5 | // * The Geant4 software is copyright of the Copyright Holders of * |
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| 6 | // * the Geant4 Collaboration. It is provided under the terms and * |
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| 7 | // * conditions of the Geant4 Software License, included in the file * |
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| 8 | // * LICENSE and available at http://cern.ch/geant4/license . These * |
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| 9 | // * include a list of copyright holders. * |
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| 10 | // * * |
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| 11 | // * Neither the authors of this software system, nor their employing * |
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| 12 | // * institutes,nor the agencies providing financial support for this * |
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| 13 | // * work make any representation or warranty, express or implied, * |
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| 14 | // * regarding this software system or assume any liability for its * |
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| 15 | // * use. Please see the license in the file LICENSE and URL above * |
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| 16 | // * for the full disclaimer and the limitation of liability. * |
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| 17 | // * * |
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| 18 | // * This code implementation is the result of the scientific and * |
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| 19 | // * technical work of the GEANT4 collaboration. * |
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| 20 | // * By using, copying, modifying or distributing the software (or * |
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| 21 | // * any work based on the software) you agree to acknowledge its * |
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| 22 | // * use in resulting scientific publications, and indicate your * |
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| 23 | // * acceptance of all terms of the Geant4 Software license. * |
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| 24 | // ******************************************************************** |
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| 25 | // |
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| 26 | // |
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| 27 | // $Id: G4ImplicitEuler.cc,v 1.9 2006/06/29 18:24:11 gunter Exp $ |
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[1231] | 28 | // GEANT4 tag $Name: $ |
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[831] | 29 | // |
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| 30 | // |
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| 31 | // Implicit Euler: |
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| 32 | // |
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| 33 | // x_1 = x_0 + h/2 * ( dx(t_0,x_0) + dx(t_0+h,x_0+h*dx(t_0,x_0) ) ) |
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| 34 | // |
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| 35 | // Second order solver. |
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| 36 | // Take the current derivative and add it to the current position. |
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| 37 | // Take the output and its derivative. Add the mean of both derivatives |
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| 38 | // to form the final output. |
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| 39 | // |
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| 40 | // W.Wander <wwc@mit.edu> 12/09/97 |
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| 41 | // |
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| 42 | // -------------------------------------------------------------------- |
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| 43 | |
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| 44 | #include "G4ImplicitEuler.hh" |
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| 45 | #include "G4ThreeVector.hh" |
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| 46 | |
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| 47 | ///////////////////////////////////////////////////////////////////////// |
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| 48 | // |
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| 49 | // Constructor |
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| 50 | |
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| 51 | G4ImplicitEuler::G4ImplicitEuler(G4EquationOfMotion *EqRhs, |
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| 52 | G4int numberOfVariables): |
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| 53 | G4MagErrorStepper(EqRhs, numberOfVariables) |
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| 54 | { |
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| 55 | unsigned int noVariables= std::max(numberOfVariables,8); // For Time .. 7+1 |
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| 56 | dydxTemp = new G4double[noVariables] ; |
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| 57 | yTemp = new G4double[noVariables] ; |
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| 58 | } |
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| 59 | |
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| 60 | |
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| 61 | //////////////////////////////////////////////////////////////////////// |
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| 62 | // |
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| 63 | // Destructor |
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| 64 | |
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| 65 | G4ImplicitEuler::~G4ImplicitEuler() |
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| 66 | { |
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| 67 | delete[] dydxTemp; |
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| 68 | delete[] yTemp; |
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| 69 | } |
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| 70 | |
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| 71 | ////////////////////////////////////////////////////////////////////// |
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| 72 | // |
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| 73 | // |
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| 74 | |
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| 75 | void |
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| 76 | G4ImplicitEuler::DumbStepper( const G4double yIn[], |
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| 77 | const G4double dydx[], |
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| 78 | G4double h, |
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| 79 | G4double yOut[]) |
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| 80 | { |
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| 81 | G4int i; |
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| 82 | const G4int numberOfVariables= GetNumberOfVariables(); |
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| 83 | |
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| 84 | // Initialise time to t0, needed when it is not updated by the integration. |
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| 85 | yTemp[7] = yOut[7] = yIn[7]; // Better to set it to NaN; // TODO |
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| 86 | |
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| 87 | for( i = 0; i < numberOfVariables; i++ ) |
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| 88 | { |
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| 89 | yTemp[i] = yIn[i] + h*dydx[i] ; |
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| 90 | } |
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| 91 | |
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| 92 | RightHandSide(yTemp,dydxTemp); |
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| 93 | |
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| 94 | for( i = 0; i < numberOfVariables; i++ ) |
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| 95 | { |
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| 96 | yOut[i] = yIn[i] + 0.5 * h * ( dydx[i] + dydxTemp[i] ); |
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| 97 | } |
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| 98 | |
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| 99 | return ; |
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| 100 | } |
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