class AliITSsimulationSPD: public AliITSsimulation

 Default constructor.
 Inputs:
    none.
 Outputs:
    none.
 Return:
    A default constructed AliITSsimulationSPD class.

 standard constructor
 Inputs:
    AliITSsegmentation *seg  A pointer to the segmentation class
                             to be used for this simulation
    AliITSCalibration     *resp A pointer to the responce class to
                             be used for this simulation
 Outputs:
    none.
 Return:
    A default constructed AliITSsimulationSPD class.

 Initilization
 Inputs:
    none.
 Outputs:
    none.
 Return:
    none.

 This function set the Tangent of the Lorentz angle.
 A weighted average is used for electrons and holes
 Input: Double_t WeightHole: wheight for hole: it should be in the range [0,1]
 output: Bool_t : kTRUE in case of success

 destructor
 Inputs:
    none.
 Outputs:
    none.
 Return:
     none.

     Copy Constructor
 Inputs:
    AliITSsimulationSPD &s The original class for which
                                this class is a copy of
 Outputs:
    none.
 Return:

    Assignment operator
 Inputs:
    AliITSsimulationSPD &s The original class for which
                                this class is a copy of
 Outputs:
    none.
 Return:

  This function creates maps to build the list of tracks for each
  summable digit. Inputs defined by base class.
  Inputs:
    Int_t module   // Module number to be simulated
    Int_t event    // Event number to be simulated
  Outputs:
    none
  Returns:
    none

  This function begins the work of creating S-Digits.  Inputs defined
  by base class.
  Inputs:
    AliITSmodule *mod  //  module
    Int_t              //  not used
    Int_t event        //  Event number
  Outputs:
    none
  Return:
    test              //  test returns kTRUE if the module contained hits
                      //  test returns kFALSE if it did not contain hits

  This function adds each S-Digit to pList
  Inputs:
    none.
  Outputs:
    none.
  Return:
    none

  This function calls SDigitsToDigits which creates Digits from SDigits
  Inputs:
    none
  Outputs:
    none
  Return
    none

  This function creates Digits straight from the hits and then adds
  electronic noise to the digits before adding them to pList
  Each of the input variables is passed along to HitToSDigit
  Inputs:
    AliITSmodule *mod     module
    Int_t                 Dummy.
    Int_t                 Dummy
  Outputs:
     none.
  Return:
    none.

 Does the charge distributions using Gaussian diffusion charge charing.
 Inputs:
    AliITSmodule *mod  Pointer to this module
 Output:
    none.
 Return:
    none.

 Does the charge distributions using Gaussian diffusion charge charing.    // Inputs:
    AliITSmodule *mod  Pointer to this module
 Output:
    none.
 Return:
    none.

 Spreads the charge over neighboring cells. Assume charge is distributed
 as charge(x,z) = (el/2*pi*sig*sig)*exp(-arg)
 arg=((x-x0)*(x-x0)/2*sig*sig)+((z-z0*z-z0)/2*sig*sig)
 if fLorentz=kTRUE, then x0=x0+ld (Lorentz drift taken into account)
 Defined this way, the integral over all x and z is el.
 Inputs:
    Double_t x0   x position of point where charge is liberated
    Double_t z0   z position of point where charge is liberated
    Int_t    ix0  row of cell corresponding to point x0
    Int_t    iz0  columb of cell corresponding to point z0
    Double_t el   number of electrons liberated in this step
    Double_t sig  Sigma difusion for this step (y0 dependent)
    Double_t ld   lorentz drift in x for this step (y0 dependent)
    Int_t    t    track number
    Int_t    ti   hit track index number
    Int_t    hi   hit "hit" index number
 Outputs:
     none.
 Return:
     none.

 Spreads the charge over neighboring cells. Assume charge is distributed
 as charge(x,z) = (el/2*pi*sigx*sigz)*exp(-arg)
 arg=((x-x0)*(x-x0)/2*sigx*sigx)+((z-z0*z-z0)/2*sigz*sigz)
 if fLorentz=kTRUE, then x0=x0+ld (Lorentz drift taken into account)
 Defined this way, the integral over all x and z is el.
 Inputs:
    Double_t x0   x position of point where charge is liberated
    Double_t z0   z position of point where charge is liberated
    Int_t    ix0  row of cell corresponding to point x0
    Int_t    iz0  columb of cell corresponding to point z0
    Double_t el   number of electrons liberated in this step
    Double_t sigx Sigma difusion along x for this step (y0 dependent)
    Double_t sigz Sigma difusion along z for this step (y0 dependent)
    Double_t ld   lorentz drift in x for this stip (y0 dependent)
    Int_t    t    track number
    Int_t    ti   hit track index number
    Int_t    hi   hit "hit" index number
 Outputs:
     none.
 Return:
     none.

 Removes dead pixels on each module (ladder)
 This should be called before going from sdigits to digits (FrompListToDigits)

 Adds noisy pixels on each module (ladder)
 This should be called before going from sdigits to digits (FrompListToDigits)

 add noise and electronics, perform the zero suppression and add the
 digit to the list
 Inputs:
    none.
 Outputs:
    none.
 Return:
    none.

 create 1D histograms for tests
 Inputs:
    none.
 Outputs:
    none.
 Return:
     none.

 Fill the histogram
 Inputs:
    none.
 Outputs:
    none.
 Return:
     none.

 Reset histograms for this detector
 Inputs:
    none.
 Outputs:
    none.
 Return:
     none.

  Take into account the coupling between adiacent pixels.
  The parameters probcol and probrow are the probability of the
  signal in one pixel shared in the two adjacent pixels along
  the column and row direction, respectively.
  Note pList is goten via GetMap() and module is not need any more.
  Otherwise it is identical to that coded by Tiziano Virgili (BSN).

   */
 Inputs:
    Int_t col            z cell index
    Int_t row            x cell index
 Outputs:
    none.
 Return:
     none.

  Take into account the coupling between adiacent pixels.
  The parameters probcol and probrow are the fractions of the
  signal in one pixel shared in the two adjacent pixels along
  the column and row direction, respectively.

   */
 Inputs:
    Int_t col            z cell index
    Int_t row            x cell index
    Int_t module         module number
 Outputs:
    none.
 Return:
     none.

 Generate randomly the strobe
 phase w.r.t to the LHC clock
 Done once per event

 This set the Lorentz drift of Electrons and Holes: by deafult equal weights to Electrons and Holes

 Getter for the Lorentz angle

 For backwards compatibility

 Standard interface to DigitiseModule  Inputs: AliITSmodule *mod  Pointer to this module

 This sets fStrobe flag and allows generating the strobe and applying it to select hits

  This function adds a signal to the pList from the pList class
  Inputs: iz column number  ix row number  trk track number  ht hit number  signal signal strength

  This function adds noise to data in the MapA2 as well as the pList
  Inputs:  iz column number  ix row number  noise electronic noise generated by FrompListToDigits

 Get a pointer to the segmentation object

 set pointer to segmentation objec

 Getters for data kept in fSegmentation and fResponse.
 Returns the Threshold in electrons

 Returns the couplings Columb and Row.

 Returns the number of pixels in x

 Returns the number of pixels in z