G4HarmonicPolMagField.cc

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// $Id$
//
// -------------------------------------------------------------------
 
#include "G4HarmonicPolMagField.hh"
#include "globals.hh"
 
G4HarmonicPolMagField::G4HarmonicPolMagField()
{
}
 
/////////////////////////////////////////////////////////////////////////  
 
G4HarmonicPolMagField::~G4HarmonicPolMagField()
{
}
 
/////////////////////////////////////////////////////////////////////////
 
 
void G4HarmonicPolMagField::GetFieldValue(const G4double yTrack[7],
                                                G4double B[3]     ) const  
{
   G4int i ;
   G4double a = 1.00 ;   // mm -> m 
   G4double x = a*yTrack[0], y = a*yTrack[1], z = a*yTrack[2] ;
   G4double x2 = x*x, y2 = y*y, z2 = z*z ;
   G4double x3 = x2*x, y3 = y2*y, z3 = z2*z ;
   G4double xy = x*y, xz = x*z, yz = y*z, xyz = x*y*z ;
   static G4double
   c[24] = {
             .010, .010, .010,                                       // 3(0)
         .0001, .0001, .0001, .0001, .0001,                      // 5(1)
         .00001, .00001, .00001, .00001, .00001, .00001, .00001, // 7(2)
         .000001, .000001, .000001, .000001, .000001, .000001,
         .0000001, .0000001, .0000001                            // 9(3)
            } ;                                            // total :   24
   
   //   for(i=0;i<24;i++)
   //   {
   //      c[i] = 1.0*c[i] ;
   //   }
   B[0] =  c[1]
          -2*c[3]*x + c[4]*z +c[6]*y -2*c[7]*x
          -6*c[8]*xz + c[9]*(z2-x2) -2*c[10]*xy + c[11]*yz - 2*c[12]*xz
          +c[13]*(y2-x2) - 6*c[14]*xy
          -4*c[15]*(3*x*z2-x3) +c[16]*(z3-3*x2*z) - 6*c[17]*xyz +c[18]*y*(z2-x2)
          -2*c[19]*(x*z2+x*y2-2*x3/3) + c[20]*z*(y2-x2) - 6*c[21]*xyz
          +c[22]*(y3-3*x2*y) - 4*c[23]*(3*x*y2-x3) ;
   
   B[1] =  c[2]
          +c[5]*z + c[6]*x + 2*c[7]*y
          +c[10]*(z2-x2) + c[11]*xz +2*c[12]*yz +2*c[13]*xy + 3*c[14]*(y2-x2)
      +c[17]*(z3-3*x2*z) + c[18]*(x*z2-x3/3) +2*c[19]*y*(z2-x2)
          +2*c[20]*xyz
          +3*c[21]*z*(y2-x2) + c[22]*(3*x*y2-x3) + 4*c[23]*(y3-3*x2*y) ;
   
   B[2] =  c[0]
          +c[3]*z + c[4]*x + c[5]*y
          +3*c[8]*(z2-x2) + 2*c[9]*xz + 2*c[10]*yz + c[11]*xy + c[12]*(y2-x2)
          +4*c[15]*(z3-3*x2*z) + c[16]*(3*x*z2-x3) + 3*c[17]*(y*z2-x2*y)
          +2*c[18]*xyz
          +2*c[19]*z*(y2-x2) + c[20]*(x*y2-x3/3) + c[21]*(y3-3*x2*y) ;
   for(i=0;i<3;i++)
   {
      B[i] = 0.1*B[i] ;
   }
}
 
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