00001 // 00002 // ******************************************************************** 00003 // * License and Disclaimer * 00004 // * * 00005 // * The Geant4 software is copyright of the Copyright Holders of * 00006 // * the Geant4 Collaboration. It is provided under the terms and * 00007 // * conditions of the Geant4 Software License, included in the file * 00008 // * LICENSE and available at http://cern.ch/geant4/license . These * 00009 // * include a list of copyright holders. * 00010 // * * 00011 // * Neither the authors of this software system, nor their employing * 00012 // * institutes,nor the agencies providing financial support for this * 00013 // * work make any representation or warranty, express or implied, * 00014 // * regarding this software system or assume any liability for its * 00015 // * use. Please see the license in the file LICENSE and URL above * 00016 // * for the full disclaimer and the limitation of liability. * 00017 // * * 00018 // * This code implementation is the result of the scientific and * 00019 // * technical work of the GEANT4 collaboration. * 00020 // * By using, copying, modifying or distributing the software (or * 00021 // * any work based on the software) you agree to acknowledge its * 00022 // * use in resulting scientific publications, and indicate your * 00023 // * acceptance of all terms of the Geant4 Software license. * 00024 // ******************************************************************** 00025 // 00026 // 00027 // $Id: G4SimpleRunge.cc 69786 2013-05-15 09:38:51Z gcosmo $ 00028 // 00029 // Simple Runge: 00030 // 00031 // x_1 = x_0 + h * ( dx( t_0+h/2, x_0 + h/2 * dx( t_0, x_0) ) ) 00032 // 00033 // Second order solver. 00034 // Takes the derivative at a position to be assumed at the middle of the 00035 // Step and adds it to the current position. 00036 // 00037 // 00038 // W.Wander <wwc@mit.edu> 12/09/97 00039 // ------------------------------------------------------------------- 00040 00041 #include "G4SimpleRunge.hh" 00042 #include "G4ThreeVector.hh" 00043 00045 // 00046 // Constructor 00047 00048 G4SimpleRunge::G4SimpleRunge(G4EquationOfMotion* EqRhs, G4int numberOfVariables) 00049 : G4MagErrorStepper(EqRhs, numberOfVariables), 00050 fNumberOfVariables(numberOfVariables) 00051 { 00052 00053 unsigned int noVariables= std::max(numberOfVariables, 00054 GetNumberOfStateVariables()); 00055 // To deal with Time >= 7+1 00056 dydxTemp = new G4double[noVariables] ; 00057 yTemp = new G4double[noVariables] ; 00058 } 00059 00060 00062 // 00063 // Destructor 00064 00065 G4SimpleRunge::~G4SimpleRunge() 00066 { 00067 delete[] dydxTemp; 00068 delete[] yTemp; 00069 } 00070 00072 // 00073 // 00074 00075 void 00076 G4SimpleRunge::DumbStepper( const G4double yIn[], 00077 const G4double dydx[], 00078 G4double h, 00079 G4double yOut[]) 00080 { 00081 // Initialise time to t0, needed when it is not updated by the integration. 00082 yTemp[7] = yOut[7] = yIn[7]; // Better to set it to NaN; // TODO 00083 00084 G4int i; 00085 00086 for( i = 0; i < fNumberOfVariables; i++ ) 00087 { 00088 yTemp[i] = yIn[i] + 0.5 * h*dydx[i] ; 00089 } 00090 00091 RightHandSide(yTemp,dydxTemp); 00092 00093 for( i = 0; i < fNumberOfVariables; i++ ) 00094 { 00095 yOut[i] = yIn[i] + h * ( dydxTemp[i] ); 00096 } 00097 }