class AliITSgeom: public TObject

     The default constructor for the AliITSgeom class. It, by default,
 sets fNlayers to zero and zeros all pointers.
 Do not allocate anything zero everything.
 Inputs:
    none.
 Outputs:
    none.
 Return:
    a zeroed AliITSgeom object.

     A simple constructor to set basic geometry class variables
 Inputs:
      Int_t itype   the type of transformation kept.
                    bit 0 => Standard GEANT
                    bit 1 => ITS tracking
                    bit 2 => A change in the coordinate system
                    has been made. others are still to be defined
                    as needed.
      Int_t nlayers The number of ITS layers also set the size of
                    the arrays
      Int_t *nlads  an array of the number of ladders for each
                    layer. This array must be nlayers long.
      Int_t *ndets  an array of the number of detectors per ladder
                    for each layer. This array must be nlayers long.
      Int_t mods    The number of modules. Typically the sum of all the
                    detectors on every layer and ladder.
 Outputs:
     none
 Return:
     A properly inilized AliITSgeom object.

     A simple Inilizer to set basic geometry class variables
 Inputs:
      Int_t itype   the type of transformation kept.
                    bit 0 => Standard GEANT
                    bit 1 => ITS tracking
                    bit 2 => A change in the coordinate system
                    has been made. others are still to be defined
                    as needed.
      Int_t nlayers The number of ITS layers also set the size of
                    the arrays
      Int_t *nlads  an array of the number of ladders for each
                    layer. This array must be nlayers long.
      Int_t *ndets  an array of the number of detectors per ladder
                    for each layer. This array must be nlayers long.
      Int_t mods    The number of modules. Typically the sum of all the
                    detectors on every layer and ladder.
 Outputs:
     none
 Return:
     A properly inilized AliITSgeom object.

 Given the translation vector tran[3] and the rotation matrix rot[1],
 this function creates and adds to the TObject Array fGm the
 AliITSgeomMatrix object.
 The rot[10] matrix is set up like:
   / rot[0]  rot[1]  rot[2] \
    //  |  rot[3]  rot[4]  rot[5]  |
    //   \ rot[6]  rot[7]  rot[8] /  if(rot[9]!=0) then the Identity matrix
    // is used regardless of the values in rot[0]-rot[8].

 Inputs:
    Int_t           mod     The module number. The location in TObjArray
    Int_t           lay     The layer where this module is
    Int_t           lad     On which ladder this module is
    Int_t           det     Which detector on this ladder this module is
    AliITSDetector idet     The type of detector see AliITSgeom.h
    Double_t       tran[3]  The translation vector
    Double_t       rot[10]  The rotation matrix.
 Outputs:
    none
 Return:
    none.

     The destructor for the AliITSgeom class. If the arrays fNlad,
 fNdet, or fGm have had memory allocated to them, there pointer values
 are non zero, then this memory space is freed and they are set
 to zero. In addition, fNlayers is set to zero. The destruction of
 Inputs:
    none.
 Outputs:
    none.
 Return:
    none.

 translation and rotation.
     The copy constructor for the AliITSgeom class. It calls the
 = operator function. See the = operator function for more details.
 Inputs:
     AliITSgeom &source  The AliITSgeom class with which to make this
                         a copy of.
 Outputs:
     none.
 Return:
     none.

     The = operator function for the AliITSgeom class. It makes an
 independent copy of the class in such a way that any changes made
 to the copied class will not affect the source class in any way.
 This is required for many ITS alignment studies where the copied
 class is then modified by introducing some misalignment.
 Inputs:
     AliITSgeom &source  The AliITSgeom class with which to make this
                         a copy of.
 Outputs:
     none.
 Return:
     *this The a new copy of source.

      This routine computes the module index number from the layer,
 ladder, and detector numbers. The number of ladders and detectors
 per layer is determined when this geometry package is constructed,
 see AliITSgeom(const char *filename) for specifics.
 Inputs:
    Int_t lay  The layer number. Starting from 1.
    Int_t lad  The ladder number. Starting from 1.
    Int_t det  The detector number. Starting from 1.
 Outputs:
    none.
 Return:
    the module index number, starting from zero.

      This routine computes the layer, ladder and detector number
 given the module index number. The number of ladders and detectors
 per layer is determined when this geometry package is constructed,
 see AliITSgeom(const char *filename) for specifics.
 Inputs:
     Int_t index  The module index number, starting from zero.
 Outputs:
     Int_t lay    The layer number. Starting from 1.
     Int_t lad    The ladder number. Starting from 1.
     Int_t det    The detector number. Starting from 1.
 Return:
     none.

 Finds and returns the number of detector types used and the
 maximum detector type value. Only counts id >=0 (no undefined
 values. See AliITSgeom.h for list of AliITSDetecor enumerated types.
 Inputs:
    none.
 Outputs:
    The maximum detector type used
 Return:
    The number of detector types used

 Finds and returns the number of detector types used and the
 number of each detector type. Only counts id >=0 (no undefined
 values. See AliITSgeom.h for list of AliITSDetecor enumerated types.
 Inputs:
    none.
 Outputs:
    The maximum detector type used
 Return:
    The number of detector types used

 returns the starting module index value for a give type of detector id.
 This assumes that the detector types are different on different layers
 and that they are not mixed up.
 Inputs:
    Int_t dtype A detector type number. 0 for SPD, 1 for SDD,
                and 2 for SSD.
 Outputs:
    none.
 Return:
    the module index for the first occurrence of that detector type.

 returns the last module index value for a give type of detector id.
 This assumes that the detector types are different on different layers
 and that they are not mixed up.
 Inputs:
     Int_t dtype A detector type number. 0 for SPD, 1 for SDD,
                 and 2 for SSD.
 Outputs:
 Return:
     the module index for the last occurrence of that detector type.

     This function prints out the coordinate transformations for
 the particular detector defined by layer, ladder, and detector
 to the file pointed to by the File pointer fp. fprintf statements
 are used to print out the numbers. The format is
 layer ladder detector Trans= fx0 fy0 fz0 rot= frx fry frz
 Shape=fShapeIndex
                         dfr= fr[0] fr[1] fr[2]
                         dfr= fr[3] fr[4] fr[5]
                         dfr= fr[6] fr[7] fr[8]
 By indicating which detector, some control over the information
 is given to the user. The output it written to the file pointed
 to by the file pointer fp. This can be set to stdout if you want.
 Inputs:
     FILE *fp           A file pointer to an opened file for
                        writing in which the results of the
                        comparison will be written.
     Int_t lay          The layer number. Starting from 1.
     Int_t lad          The ladder number. Starting from 1.
     Int_t det          The detector number. Starting from 1.
 Outputs:
     none
 Return:
     none.

      Finds the Detector (Module) that is nearest the point g [cm] in
 ALICE Global coordinates. If layer !=0 then the search is restricted
 to Detectors (Modules) in that particular layer.
 Inputs:
     Double_t g[3]  The ALICE Cartesian global coordinate from which the
                    distance is to be calculated with.
     Int_t lay      The layer to restrict the search to. If layer=0 then
                    all layers are searched. Default is lay=0.
 Output:
     none.
 Return:
     The module number representing the nearest module.

      Finds 27 Detectors (Modules) that are nearest the point g [cm] in
 ALICE Global coordinates. If layer !=0 then the search is restricted
 to Detectors (Modules) in that particular layer. The number 27 comes
 from including the nearest detector and all those around it (up, down,
 left, right, forwards, backwards, and the corners).
 Input:
     Double_t g[3]  The ALICE Cartesian global coordinate from which the
                    distance is to be calculated with.
     Int_t lay      The layer to restrict the search to. If layer=0 then
                    all layers are searched. Default is lay=0.
 Output:
     Int_t n[27]    The module number representing the nearest 27 modules
                    in order.
 Return:
     none.

Conversion from local coordinates on detectors to local
coordinates used for tracking ("v2")
 Inputs:
   Int_t   md      Module number
   Float_t xin     Standard local coordinate x
   Float_t zin     Standard local coordinate z
 Output:
   Float_t yout    Tracking local coordinate y
   Float_t zout    Tracking local coordinate z
 Return:
   none.

Conversion from local coordinates used for tracking ("v2") to
local detector coordinates
 Inputs:
   Int_t   md      Module number
   Float_t yin     Tracking local coordinate y
   Float_t zin     Tracking local coordinate z
 Output:
   Float_t xout    Standard local coordinate x
   Float_t zout    Standard local coordinate z
 Return:
   none.

 Getters

 returns kTRUE if the transformation defined by this class is
 for Global GEANT coordinate system to the local GEANT coordinate system
 of the detector. These are the transformation used by GEANT.

 returns kTRUE if the transformation defined by this class is
 for Global GEANT coordinate system to the local "Tracking" coordinate
 system of the detector. These are the transformation used by the
 Tracking code.

 returns kTRUE if the transformation defined by this class is
 for Global GEANT coordinate system to the local GEANT coordinate system
 of the detector but may have been displaced by some typically small
 amount. These are modified transformation similar to that used by GEANT.

     This function returns a pointer to the particular AliITSgeomMatrix
 class for a specific module index.

 This function find and return the number of detector types only.

     This function returns the number of detectors/ladder for a give
 layer. In particular it returns fNdet[layer-1].

     This function returns the number of ladders for a give layer. In
 particular it returns fNlad[layer-1].

     This function returns the number of layers defined in the ITS
 geometry. In particular it returns fNlayers.

     This function returns the module index number given the layer,
 ladder and detector numbers put into the array id[3].

 Returns the detector type
Int_t GetModuleType(Int_t index)const{
    return GetGeomMatrix(index)->GetDetectorIndex();}

 Returns the detector type as a string

 Returns the detector type as a string

     Returns the starting module index number for SPD detector,
 assuming the modules are placed in the "standard" cylindrical
 ITS structure.

     Returns the ending module index number for SPD detector,
 assuming the modules are placed in the "standard" cylindrical
 ITS structure.

     Returns the starting module index number for SDD detector,
 assuming the modules are placed in the "standard" cylindrical
 ITS structure.

     Returns the ending module index number for SDD detector,
 assuming the modules are placed in the "standard" cylindrical
 ITS structure.

     Returns the starting module index number for SSD detector,
 assuming the modules are placed in the "standard" cylindrical
 ITS structure.

     Returns the ending module index number for SSD detector,
 assuming the modules are placed in the "standard" cylindrical
 ITS structure.

     Returns the last module index number.

     This function returns the rotation angles for a give module
 in the Double point array ang[3]. The angles are in radians

     This function returns the rotation angles for a give module
 in the three floating point variables provided. rx = frx,
 fy = fry, rz = frz. The angles are in radians

     This function returns the rotation angles for a give detector on
 a give ladder in a give layer in the three floating point variables
 provided. rx = frx, fy = fry, rz = frz. The angles are in radians

     This function returns the 6 GEANT rotation angles for a give
 module in the double point array ang[3]. The angles are in degrees

     This function returns the Cartesian translation for a give
 module in the Double array t[3]. The units are
 those of the Monte Carlo, generally cm.

     This function returns the Cartesian translation for a give
 module index in the three floating point variables provided.
 x = fx0, y = fy0, z = fz0. The units are those of the Mont
 Carlo, generally cm.

     This function returns the Cartesian translation for a give
 detector on a give ladder in a give layer in the three floating
 point variables provided. x = fx0, y = fy0, z = fz0. The units are
 those of the Monte Carlo, generally cm.

     This function returns the Cartesian translation for a give
 module in the Double array t[3]. The units are
 those of the Monte Carlo, generally cm.

     This function returns the Cartesian translation for a give
 module index in the three floating point variables provided.
 x = fx0, y = fy0, z = fz0. The units are those of the Mont
 Carlo, generally cm.

     This function returns the Cartesian translation for a give
 detector on a give ladder in a give layer in the three floating
 point variables provided. x = fx0, y = fy0, z = fz0. The units are
 those of the Monte Carlo, generally cm.

      This function returns the Cartesian translation [cm] and the
 6 GEANT rotation angles [degrees]for a given layer ladder and
 detector number, in the TVector x (at least 9 elements large).
 This function is required to be in-lined for speed.

     This function returns the rotation matrix in Double
 precision for a given module.

     This function returns the rotation matrix in a Double
 precision pointer for a given module. mat[i][j] => mat[3*i+j].

     This function returns the rotation matrix in a floating
 precision pointer for a given layer ladder and detector module.
 mat[i][j] => mat[3*i+j].

     This function returns the rotation matrix in a Double
 precision pointer for a given layer ladder and detector module.
 mat[i][j] => mat[3*i+j].

     This function sets the rotation matrix in a Double
 precision pointer for a given module. mat[i][j] => mat[3*i+j].

 Return the normal for a specific module

  Setters
     Sets the rotation angles and matrix for a give module index
 via the double precision array a[3] [radians].

     Sets the rotation angles and matrix for a give module index
 via the 3 floating precision variables rx, ry, and rz [radians].

     Sets the rotation angles and matrix for a give layer, ladder,
 and detector numbers via the 3 floating precision variables rx,
 ry, and rz [radians].

     Sets the rotation angles and matrix for a give module index
 via the Double precision array a[6] [degree]. The angles are those
 defined by GEANT 3.12.

     Sets the rotation angles and matrix for a give layer, ladder
 and detector, in the array id[3] via the Double precision array
 a[6] [degree]. The angles are those defined by GEANT 3.12.

     Sets the rotation angles and matrix for a give layer, ladder
 and detector, via the Double precision array a[6] [degree]. The
 angles are those defined by GEANT 3.12.

     This function sets a new translation vector, given by the
 array x[3], for the Cartesian coordinate transformation
 for a give module index.

     This function sets a new translation vector, given by the three
 variables x, y, and z, for the Cartesian coordinate transformation
 for the detector defined by layer, ladder and detector.

  transformations
     Transforms from the ALICE Global coordinate system
 to the detector local coordinate system for the detector
 defined by the layer, ladder, and detector numbers. The
 global and local coordinate are given in two floating point
 arrays g[3], and l[3].

     Transforms from the ALICE Global coordinate system
 to the detector local coordinate system for the detector
 defined by the id[0], id[1], and id[2] numbers. The
 global and local coordinate are given in two floating point
 arrays g[3], and l[3].

     Transforms from the ALICE Global coordinate system
 to the detector local coordinate system for the detector
 module index number. The global and local coordinate are
 given in two floating point arrays g[3], and l[3].

     Transforms from the ALICE Global coordinate system
 to the detector local coordinate system for the detector
 defined by the layer, ladder, and detector numbers. The
 global and local coordinate are given in two Double point
 arrays g[3], and l[3].

     Transforms from the ALICE Global coordinate system
 to the detector local coordinate system for the detector
 defined by the id[0], id[1], and id[2] numbers. The
 global and local coordinate are given in two Double point
 arrays g[3], and l[3].

 Returns the distance [cm] between the point g[3] and the center of
 the detector/module specified by the the module index number.