code: def meanOmega(self,dangle,oned=False,offset_sign=None,
                    tdisrupt=None):
          
          if offset_sign is None: offset_sign= self._sigMeanSign
          if tdisrupt is None: tdisrupt= self._tdisrupt
          dOmin= dangle/tdisrupt
          meandO= self._meandO
          dO1D= ((numpy.sqrt(2./numpy.pi)*numpy.sqrt(self._sortedSigOEig[2])\
                     *numpy.exp(-0.5*(meandO-dOmin)**2.\
                                     /self._sortedSigOEig[2])/
                  (1.+special.erf((meandO-dOmin)\
                                      /numpy.sqrt(2.*self._sortedSigOEig[2]))))\
                     +meandO)
          if oned: return dO1D
          else:
              return self._progenitor_Omega+dO1D*self._dsigomeanProgDirection\
                  *offset_sign
docs: NAME:
  
             meanOmega
  
          PURPOSE:
  
             calculate the mean frequency as a function of angle, assuming a uniform time distribution up to a maximum time
  
          INPUT:
  
             dangle - angle offset
  
             oned= (False) if True, return the 1D offset from the progenitor (along the direction of disruption)
  
             offset_sign= sign of the frequency offset (shouldn't be set)
  
          OUTPUT:
  
             mean Omega
  
          HISTORY:
  
             2013-12-01 - Written - Bovy (IAS)