class AliGenAfterBurnerFlow: public AliGenerator

 Default Construction

 reactionPlane - Reaction Plane Angle given in Deg [0-360]
 but stored and applied in radiants (standard for TParticle & AliCollisionGeometry)

 def. dest.

 Set Directed Flow
 The same directed flow is applied to all specified particles
 independently on transverse momentum or rapidity

 PDG - particle type to apply directed flow
       if (PDG == 0) use as default

 Set Directed Flow
 Directed flow is parameterised as follows

 V1(Pt,Y) = (V11 + V12*Pt) * sign(Y) * (V13 + V14 * abs(Y)^3)

 where sign = 1 for Y > 0 and -1 for Y < 0

 Defaults values
 v12 = v14 = 0
 v13 = 1

 PDG - particle type to apply directed flow
       if (PDG == 0) use as default

 Set Elliptic Flow
 The same Elliptic flow is applied to all specified particles
 independently on transverse momentum or rapidity

 PDG - particle type to apply directed flow
       if (PDG == 0) use as default

 V2 - flow coefficient

 NOTE: for starting playing with FLOW
       start with this function and values 0.05 - 0.1

 Set Elliptic Flow

 Elliptic flow is parametrised to reproduce
 V2 of Pions at RHIC energies and is given by:

 V2 = (v00 + v10*pt + v11*pt^2) * exp (-v22 * y^2) and zero if V2<0.

 Set Elliptic Flow

 Elliptic flow is parametrised to reproduce
 V2 of Pions at RHIC energies and is given by:

 V2 = v21 * (pT/pTMax ) * exp (-v22 * y^2)    where pT <= pTmax
      v21 * exp (-v22 * y^2)                  where pT > pTmax

 v21   - value at saturation
 pTmax - saturation transverse momentum
 v22   - rapidity decreasing

 Set Elliptic Flow

 Elliptic flow is parameterised using
 old MevSim parameterisation

 V2 = (V21 + V22 pT^2) * exp (-v22 * y^2)

 Set npart parameterization.

 private function

 Standard AliGenerator Initializer

 private function
 Return Flow Coefficient for a given particle type flow order
 and particle momentum (Pt, Y)

 Calculate npart norm.

 Init the primary particle list

 AliGenerator generate function doing actual job.
 Algorythm:

 1. loop over particles on the stack and choose primaries
 2. calculate delta phi
 3. change phi of primary particle and if it is non-stable
    then its daughters' phi and vertex also

 For more details see :
 M.G. Poghosyan
 PWG2 meeting on 06.05.2008 and 03.06.2008

 Rotation