sign of b1 multipole in quad (sextu..) wrong? about at HOT 2 OPEN

static void strthinkick(double* r, const double* A, const double* B, double L, int max_order)
/***************************************************************************** 
 Calculate and apply a multipole kick to a 6-dimentional
 phase space vector in a straight element (quadrupole)
 
 IMPORTANT !!!
 The reference coordinate system is straight but the field expansion may still
 contain dipole terms: PolynomA(1), PolynomB(1) - in MATLAB notation,
 A[0], B[0] - C,C++ notation
 
 ******************************************************************************/
{
   int i;
   double ReSum = B[max_order];
   double ImSum = A[max_order];
   double ReSumTemp;
   for (i=max_order-1; i>=0; i--) {
      ReSumTemp = ReSum*r[0] - ImSum*r[2] + B[i];
      ImSum = ImSum*r[0] +  ReSum*r[2] + A[i];
      ReSum = ReSumTemp;
   }
   r[1] -=  L*ReSum;
   r[3] +=  L*ImSum;
}