class HMdcSizesCellsLayer: public HMdcPlane

 Constructor creates an array of pointers of type HMdcSizesCellsCell

 destructor

 alignTrans: coord. system of layer will transformed to "alignTrans" sys.

 return point on the layer plane in wire float number scale!

  calculation the the cell number for the point x,y
  on the wire plane. (x,y - in coor. sys. of layer, z=0)

 HMdcLineParam ln must be in sector coor.system
 return +1 if line path OVER wire in layer(mdc,sector) coor.system
 return -1 if line path UNDER wire in layer(mdc,sector) coor.system
 return 0. if cell<0 or cell>=nCells in layer

 Calculate cells crossed by GeantMdc hit (x,y,theta,phi) for mdc digitizer.
 return kFALSE if no cells crossed
 return x,y corrected to the layer plane
 Correction for HGeantMdc hit Z position! (zGeantHit)

 calculation of cells crossed by line "ln"
 ln - sector coordinate system

  return: y of the cross point of line "ln" with layer in coor.sys. of rotated layer
  and abs(tanAlpha)- alpha is impact angle of "ln"

 calculation of cells crossed by line x1,y1,z1-x2,y2,z2
 x1,y1,z1, x2,y2,z2 - sector coordinate system

 calculation of cells crossed by line x1,y1,z1 - x2,y2,z2
 x1,y1,z1, x2,y2,z2 - sector coordinate system

 return kTRUE if crossed cell number >=0 and < nCells_in_layer
 return region of crossed cells: firstCell - lastCell
 and track path in cells:
 firstCellPath for cell=firstCell
 midCellPath   for firstCell<cell<lastCell
 lastCellPath  for cell=lastCell

 midCellPath  = 0 if one or two cells crossed only
 lastCellPath = 0 if one cell crossed only

 Exmaple:
  HMdcSizesCells* pSizesCell;
  HMdcSizesCellsLayers &sizesCellsLayer = (*pSizesCell)[sector][module][layer];
  Int_t firstCell,lastCell;
  Float_t firstCellPath,midCellPath,lastCellPath;
  if(sizesCellsLayer->calcCrossedCells(x1,y1,z1,x2,y2,z2,firstCell,lastCell,
                                       firstCellPath,midCellPath,lastCellPath) {
    Float_t totalePathInLayer = 0.;
    for(Int_t c=firstCell;c<=lastCell;++c) {
      Float_t cellPath;
      if   (c == firstCell) cellPath = firstCellPath;
      else (c == lastCell)  cellPath = lastCellPath;
      else                  cellPath = midCellPath;
      totalePathInLayer += cellPath;

    }
  }
 Transform line to the layer coor.system:

 calculation of cells crossed by line z,r,theta,phi (parameters of HMdcSeg)
    z,r [mm]   theta,phi [rad]

 return kTRUE if crossed cell number >=0 and < nCells_in_layer
 return region of crossed cells: firstCell - lastCell
 and track path in cells:
 firstCellPath for cell=firstCell
 midCellPath   for firstCell<cell<lastCell
 lastCellPath  for cell=lastCell

 midCellPath  = 0 if one or two cells crossed only
 lastCellPath = 0 if one cell crossed only

 Exmaple:
  HMdcSizesCells* pSizesCell;
  HMdcSizesCellsLayers &sizesCellsLayer = (*pSizesCell)[sector][module][layer];
  Int_t firstCell,lastCell;
  Float_t firstCellPath,midCellPath,lastCellPath;
  if(sizesCellsLayer->calcCrossedCells(Zmin,Rmin,theta,phi,firstCell,lastCell,
                                       firstCellPath,midCellPath,lastCellPath) {
    Float_t totalePathInLayer = 0.;
    for(Int_t c=firstCell;c<=lastCell;++c) {
      Float_t cellPath;
      if   (c == firstCell) cellPath = firstCellPath;
      else (c == lastCell)  cellPath = lastCellPath;
      else                  cellPath = midCellPath;
      totalePathInLayer += cellPath;

    }
  }

 calculation of cells crossed by line "ln"
 ln - sector coordinate system

 calculation of cells crossed by line "v"
 v[0-2] = x,y,z - point of line
          dx,dy,dz - direction of line
 v[3] = dx/dz;
 v[4] = dy/dz;

 transformation to coor. sys. of rotated layer from sector sys.

 return the angle alpha (in degree) between projection of line p1-p2
 on the Y-Z plane and Y axis in coor.sys. of wires in degree.
 p1,p2 in coordinate system of sector.

 return the minimal distance from line (p1-p2) to wire.
 p1,p2 are in coordinate system of sector.

 calc. the angle alpha (in degree) between projection of line p1-p2
 on the Y-Z plane and Y axis in coor.sys. of wire (y=z=0) and
 the minimal distance from line (p1-p2) to wire.
 p1,p2 - in sector coor.sys.

 p1l,p2l - in ROTATED LAYER COOR.SYS.!!!
 calc. the angle alpha (in degree) between projection of line p1-p2
 on the Y-Z plane and Y axis in coor.sys. of wire (y=z=0) and
 the minimal distance from line (p1-p2) to wire.

 calc. the angle alpha (in degree) between projection of line
 x1,y1,z1-x2,y2,z2 on the Y-Z plane and Y axis in coor.sys.
 of wires and the minimal distance from line x1,y1,z1-x2,y2,z2
 to wire.
 x1,y1,z1,x2,y2,z2 - in sector coor.sys.

 return kTRUE if line x1,y1,z1-x2,y2,z2 intersect cell or kFALSE
 if not intersect and calc. the angle alpha (in degree) between projection
 of the line  x1,y1,z1-x2,y2,z2 on the Y-Z plane and Y axis in coor.
 sys. of wires and the minimal distance from line x1,y1,z1-x2,y2,z2
 to wire.
 x1,y1,z1,x2,y2,z2 - in sector coor.sys.

 return X position of the signal on the wire in coor. sys. of this wire
 (Ywire=0, Zwire=0), x1,y1,z1 & x2,y2,z2 - track in sector coor.system

 return the path of signal along wire number "cell"
 x1,y1,z1 & x2,y2,z2 - track in sector coor.system
 Path can be <0. or > wire_length !!!
 For GEANT data and don't connected wires return 0.

 return X position of the signal on the wire in coor. sys. of this wire
 (Ywire=0, Zwire=0), "ln" - track in sector coor.system

 return the path of signal along wire number "cell"
 "ln" - track in sector coor.system
 Path can be <0. or > wire_length !!!
 For GEANT data and don't connected wires return 0.

 return the path of signal along wire number "cell"
 x1,y1,z1 & x2,y2,z2 - track in sector coor.system
 For GEANT data and don't connected wires return 0.

 outside:
 if(path<0) outside=-path;
 else if(path>wire_length) outside=path-wire_length;
 else outside=0;

 path-outside give new path which >=0. and <=wire_length)

 return kTRUE if line p1-p2 intersect cell or kFALSE if not intersect
 calc. the angle driftAlpha (in degree) and drift distance in cell
 from line (p1-p2) to wire.
 p1,p2 - in sector coor.sys.
 1)
    Z^
     |  |------------*----|
     |  | cell        *   |
     |  |            / *  |
     |  |           /90 * |
     |  | driftDist/     *|
     |  |         /       *
   --|--|--------*^-----/-|*--------->
     |  |              /  | *        Y
     |  |      alphaDrDist|  *
        |                 |   *
        |                 |    *
        |-----------------|     * track

 2)             *** 90
    Z^             ***
     |  |----------:--***-|
     |  | cell     :  /  ***
     |  |         :  /    | ***  track
     |  |         : /     |    ***
     |  | driftDist/      |
     |  |        :/       |
   --|--|--------*^-------|---------->
     |  |         |       |          Y
     |  |                 |  alphaDrDist ???
        |                 |
        |                 |
        |-----------------|


 3)                        *
                            *
    Z^                     / * <-- no eg. 90 deg. !
     |  |-----------------/   *
     |  | cell           /|    *
     |  |               / |     *
     |  |              /  |      *
     |  |   driftDist /   |       *
     |  |            /    |        *track
     |  |           /     |         *
     |  |          /      |          *
     |  |         /       |      Alpha*
   --|--|--------*^-------|------------->
     |  |         |       |          Y
     |  |      alphaDrDist|
        |                 |
        |                 |
        |                 |
        |                 |
        |                 |
        |                 |
        |-----------------|

 if "ln"  is in another sector coor.sys

 Input:  xi,yi - layer coor.sys.
 Return X in  rotated layer coor.sys.

 Input:  xi,yi - layer coor.sys.
 Return Y in  rotated layer coor.sys.

Inlines

 transform. point x,y,z from sector coor.sys. to layer coor.sys.

 transform. point x,y,z from layer coor.sys. to sector coor.sys.

 Return Y in rot.layer coor.sys.

 return cell number for y
 y must be on the layer plane and in the rot.layer.coor.sys. !
 Don't take into account layer SecondPart !
 Use it for MDC plane I & II ONLY!
 Now it is used in HMdcLookUpTb for vertex finder only.

 return cell number for point p
 It assume that "p" belong the layer plane and in the sector coor.system !
 Don't take into account layer SecondPart !
 Use it for MDC plane I & II ONLY!
 Now it is used in HMdcLookUpTb for vertex finder and offVertex track finder only.

 calc.  the minimal distance from line x1,y1,z1-x2,y2,z2  to wire.
 x1,y1,z1,x2,y2,z2 - in sector coor.sys.

 Output: yw,zw - in wire coor.sys.
 Wire coor.sys. is line y=z=0, Y - along layer
 x,y,z - in sector coor.sys.

 calc. the minimal distance from line (y1,z1) - (y2,z2)  to poin
 y=z=0 in plane y-z.

 calc. the angle alpha (in degree) between line (y1,z1) - (y2,z2)
 in Y-Z plane and Y axis and the minimal distance from this line
 to poin y=z=0 in plane y-z.

 Input:  xi,yi,zi - sector coor.sys.
 Output: xo,yo,zo - layer coor.sys.

 rotation by rotation martix "trans"

 rotation by rotation martix "trans"

 Input:  xi,yi,zi - sector coor.sys.
 Output: yo,zo - rotated layer coor.sys.

 Input:  xi,yi,zi - sector coor.sys.
 Output: yo,zo - rotated layer coor.sys.

 calc. the angle alpha (in degree) between projection of line
 "ln" on the Y-Z plane and Y axis in coor.sys.
 of wires and the minimal distance from "ln" to wire.
 "ln" - in sector coor.sys.

 calc. the angle alpha (in degree) between projection of line
 "ln" on the Y-Z plane and Y axis in coor.sys.
 of wires and the minimal distance from "ln" to wire.
 "ln" - in sector coor.sys.

 calc. the angle alpha (in degree) between projection of line
 "ln" on the Y-Z plane and Y axis in coor.sys.
 of wires and the minimal distance from "ln" to wire.
 "ln" - in sector coor.sys.

 calc. the angle alpha (in degree) between projection of line
 "ln" on the Y-Z plane and Y axis in coor.sys. of wire

 return kTRUE if line x1,y1,z1-x2,y2,z2 intersect cell or kFALSE
 if not intersect and calc. the angle alpha (in degree) between projection
 of the line  x1,y1,z1-x2,y2,z2 on the Y-Z plane and Y axis in coor.
 sys. of wires and the minimal distance from line x1,y1,z1-x2,y2,z2
 to wire.
 x1,y1,z1,x2,y2,z2 - in sector coor.sys.

 return kTRUE if line x1,y1,z1-x2,y2,z2 intersect cell or kFALSE
 if not intersect and calc. the angle alpha (in degree) between projection
 of the line  x1,y1,z1-x2,y2,z2 on the Y-Z plane and Y axis in coor.
 sys. of wires and the minimal distance from line x1,y1,z1-x2,y2,z2
 to wire.
 x1,y1,z1,x2,y2,z2 - in sector coor.sys.

 Replacment for TMath::ATan2(dz,dy)*TMath::RadToDeg()
 Return angle alpha (in degree) for the tan(alpha)=abs(dz/dy)
 Accuracy: <0.6*10^-4 deg.
 alpha is in the range 0-90 deg.

 Next method are intrested for geant data only, because plane of
 HMdcGeant hits is entrance plane of sensitive wires volume!

    inline static Double_t calcAlphaDeg(Double_t dydz);