class HMdcHitF: public HReconstructor

_HADES_CLASS_DESCRIPTION

HMdcHitF is the reconstructor that transforms the calibrated
hits in one mdc module (HMdcCal3) in segments (HMdcHitAux).
It contains the parameter of the fit (maximum chi2 allowed, minimum
number of hits required in a segment...), a pointer to the calibrated
data to be fitted, to the corresponding geometry, and the collection
of segments obtained from the fit.
It contains the following functions:
- a default constructor: initializes  minNumHits = 4,  maxChi = 1,
maxNumCommonHits = 3
- HMdcHitF(HMatrixCategory* data, HMdcModuleGeometry* mdcGeo):
Constructor:
- sets the minimum number of hits to 4
- sets the maximum chi2 to 1.
- mdcCal points to the data passed as argument, and the
appropiate setup is done
- geo points to mdcGeo, the geometry passed as argument
    - HMdcHitF(HCategory* data,HMdcModuleGeometry* mdcGeo,HCategory* seg)
Constructor:
- sets the minimum number of hits to 4
- sets the maximum chi2 to 1.
- mdcCal points to the data passed as argument, and the
appropiate setup is done
- geo points to mdcGeo, the geometry passed as argument
- mdcSegments points to seg, the segments category
- a default destructor
- setMinNumHits(Int_t min): sets minimum number of hits to min.
If min < 4, sets minimum number of hits to 4, and an error
message is printed
- fit(HMdcCal3* listCal[6], Int_t listPlanes[6], Int_t numHits):
General Least Squares fit to get slopes and intercepts in 2
projections plus their variances. It is based on the FORTRAN
subroutine STFIT1.
Fits the calibrated data of listCal and stores the result of
the fit in a segment.
- checkFit(HMdcHitAux* segment): Checks the fit: returns TRUE if
* the number of hits in the segment is greater or equal than
minNumHits.
and
* the chi2 of the fit is not greater than maxChi.
- find(Int_t listPlanes[6], Int_t nWantedHits, Int_t seg):
Finds segments with hits belonging to the planes listed in the
nWantedHits first elements of listPlanes. The segments, once
they pass several checks, are stored in the collection of
segments, starting in the position given by seg.
The basic procedure is the following:
* find hits in planes listPlanes[0] .. listPlanes[3].
* calculate the parameters of the straight line defined by
these hits
* looks for hits Int_t listPlanes[4] and/or listPlanes[5]
(depending on nWantedHits), that are close to the
intersection of that line with these planes.
* call the fit function with this collection of hits.
* if the segment passes checkFit and checkCommon then it is
added to the collection of segments in the position
indicated by seg, and seg is incremented.
- markHits(Int_t first, Int_t last):  mark used-hits in segments
in the positions between first and last in the collection of
segments.
- checkCommon(HMdcHitAux* thissegment):  check if thissegment
has common hits with other segments in the collection of
segments. If some other segment (let's call it oldsegment) is
found with at least maxNumCommonHits in common with
         thissegment, then the chi-square of the segments are compared,
and the one with lower chi-square is keeped in the collection
of segments :
* if the lower chi-square belongs to thissegment, then
oldsegment is marked to be deleted and then the function
returns FALSE. After that, in find function, thissegment
will be added to the collection of segments
* if the lower chi-square corresponds to oldsegment, then
the function returns TRUE, and thissegment will not be
added to the collection of segments in the find function
- printSegments(ofstream& file): print information about the
segments in the segments collection to file
- execute(void):finds combination of planes where to search for
hits, and calls the function find with this combination.
- plotResid (Int_t plane, Text_t* filename= "res1.root",
Text_t* hisname="hres", Int_t nbinsx =100,
Axis_t xlow = -0.05, Axis_t xup=0.05):
Calculates residues (fitted coordinate - measured coordinate)
         in the plane number "plane". These residues fill an histogram,
and the histogram is stored as "hisname"(default:"hres") in
file "filename"(default:"res1.root"). The histogram will have
"nbinsx" bins in x axis (default: 100), and the range of x
coordinate is (xlow,xup) (default: (-0.05,0.05)