class RooDataHist: public RooAbsData, public RooDirItem

 Default constructor

 Constructor of an empty data hist from a RooArgSet defining the dimensions
 of the data space. The range and number of bins in each dimensions are taken
 from getMin()getMax(),getBins() of each RooAbsArg representing that
 dimension.

 For real dimensions, the fit range and number of bins can be set independently
 of the plot range and number of bins, but it is advisable to keep the
 ratio of the plot bin width and the fit bin width an integer value.
 For category dimensions, the fit ranges always comprises all defined states
 and each state is always has its individual bin

 To effective achive binning of real dimensions with variable bins sizes,
 construct a RooThresholdCategory of the real dimension to be binned variably.
 Set the thresholds at the desired bin boundaries, and construct the
 data hist as function of the threshold category instead of the real variable.

 Constructor of a data hist from an existing data collection (binned or unbinned)
 The RooArgSet 'vars' defines the dimensions of the histogram.
 The range and number of bins in each dimensions are taken
 from getMin()getMax(),getBins() of each RooAbsArg representing that
 dimension.

 For real dimensions, the fit range and number of bins can be set independently
 of the plot range and number of bins, but it is advisable to keep the
 ratio of the plot bin width and the fit bin width an integer value.
 For category dimensions, the fit ranges always comprises all defined states
 and each state is always has its individual bin

 To effective achive binning of real dimensions with variable bins sizes,
 construct a RooThresholdCategory of the real dimension to be binned variably.
 Set the thresholds at the desired bin boundaries, and construct the
 data hist as function of the threshold category instead of the real variable.

 If the constructed data hist has less dimensions that in source data collection,
 all missing dimensions will be projected.

 Constructor of a data hist from a map of TH1,TH2 or TH3 that are collated into a x+1 dimensional
 RooDataHist where the added dimension is a category that labels the input source as defined
 in the histMap argument. The state names used in histMap must correspond to predefined states
 'indexCat'

 The RooArgList 'vars' defines the dimensions of the histogram.
 The ranges and number of bins are taken from the input histogram and must be the same in all histograms

 Constructor of a data hist from a map of RooDataHists that are collated into a x+1 dimensional
 RooDataHist where the added dimension is a category that labels the input source as defined
 in the histMap argument. The state names used in histMap must correspond to predefined states
 'indexCat'

 The RooArgList 'vars' defines the dimensions of the histogram.
 The ranges and number of bins are taken from the input histogram and must be the same in all histograms

 Constructor of a data hist from an TH1,TH2 or TH3
 The RooArgSet 'vars' defines the dimensions of the histogram. The ranges
 and number of bins are taken from the input histogram, and the corresponding
 values are set accordingly on the arguments in 'vars'

 Constructor of a binned dataset from a RooArgSet defining the dimensions
 of the data space. The range and number of bins in each dimensions are taken
 from getMin() getMax(),getBins() of each RooAbsArg representing that
 dimension.

 This constructor takes the following optional arguments

 Import(TH1&, Bool_t impDens) -- Import contents of the given TH1/2/3 into this binned dataset. The
                                 ranges and binning of the binned dataset are automatically adjusted to
                                 match those of the imported histogram.

                                 Please note: for TH1& with unequal binning _only_,
                                 you should decide if you want to import the absolute bin content,
                                 or the bin content expressed as density. The latter is default and will
                                 result in the same histogram as the original TH1. For certain type of
                                 bin contents (containing efficiencies, asymmetries, or ratio is general)
                                 you should import the absolute value and set impDens to kFALSE


 Weight(Double_t)          -- Apply given weight factor when importing histograms

 Index(RooCategory&)       -- Prepare import of multiple TH1/1/2/3 into a N+1 dimensional RooDataHist
                              where the extra discrete dimension labels the source of the imported histogram
                              If the index category defines states for which no histogram is be imported
                              the corresponding bins will be left empty.

 Import(const char*, TH1&) -- Import a THx to be associated with the given state name of the index category
                              specified in Index(). If the given state name is not yet defined in the index
                              category it will be added on the fly. The import command can be specified
                              multiple times.
 Import(map<string,TH1*>&) -- As above, but allows specification of many imports in a single operation

 Import data from given TH1/2/3 into this RooDataHist

 Import data from given set of TH1/2/3 into this RooDataHist. The category indexCat labels the sources
 in the constructed RooDataHist. The stl map provides the mapping between the indexCat state labels
 and the import source

 Import data from given set of TH1/2/3 into this RooDataHist. The category indexCat labels the sources
 in the constructed RooDataHist. The stl map provides the mapping between the indexCat state labels
 and the import source

 Adjust binning specification on first and optionally second and third
 observable to binning in given reference TH1. Used by constructors
 that import data from an external TH1

 Initialization procedure: allocate weights array, calculate
 multipliers needed for N-space to 1-dim array jump table,
 and fill the internal tree with all bin center coordinates

 Copy constructor

 Constructor of a data hist from (part of) an existing data hist. The dimensions
 of the data set are defined by the 'vars' RooArgSet, which can be identical
 to 'dset' dimensions, or a subset thereof. Reduced dimensions will be projected
 in the output data hist. The optional 'cutVar' formula variable can used to
 select the subset of bins to be copied.

 For most uses the RooAbsData::reduce() wrapper function, which uses this constructor,
 is the most convenient way to create a subset of an existing data

 Construct a clone of this dataset that contains only the cached variables

 Implementation of RooAbsData virtual method that drives the RooAbsData::reduce() methods

 Destructor

 Calculate the index for the weights array corresponding to
 to the bin enclosing the current coordinates of the internal argset

 Debug stuff, should go...

 Back end function to plotting functionality. Plot RooDataHist on given
 frame in mode specified by plot options 'o'. The main purpose of
 this function is to match the specified binning on 'o' to the
 internal binning of the plot observable in this RooDataHist.

 Return the weight at given coordinates with optional
 interpolation. If intOrder is zero, the weight
 for the bin enclosing the coordinates
 contained in 'bin' is returned. For higher values,
 the result is interpolated in the real dimensions
 of the dataset

 Return the error on current weight

 Perform boundary safe 'intOrder'-th interpolation of weights in dimension 'dim'
 at current value 'xval'

 Increment the weight of the bin enclosing the coordinates given
 by 'row' by the specified amount. Add the sum of weights squared
 for the bin by 'sumw2' rather than wgt^2

 Increment the weight of the bin enclosing the coordinates
 given by 'row' by the specified amount. Associate errors
 [wgtErrLo,wgtErrHi] with the event weight on this bin.

 Increment the weight of the bin enclosing the coordinates
 given by 'row' by the specified amount. Associate errors
 [wgtErrLo,wgtErrHi] with the event weight on this bin.

 Increment the weight of the bin enclosing the coordinates
 given by 'row' by the specified amount. Associate errors
 [wgtErrLo,wgtErrHi] with the event weight on this bin.

 Add all data points contained in 'dset' to this data set with given weight.
 Optional cut string expression selects the data points to be added and can
 reference any variable contained in this data set

 Add all data points contained in 'dset' to this data set with given weight.
 Optional RooFormulaVar pointer selects the data points to be added.

 Return the sum of the weights of all hist bins.

 If correctForBinSize is specified, the sum of weights
 is multiplied by the N-dimensional bin volume,
 making the return value the integral over the function
 represented by this histogram

 Return the sum of the weights of a multi-dimensional slice of the histogram
 by summing only over the dimensions specified in sumSet.

 The coordinates of all other dimensions are fixed to those given in sliceSet

 If correctForBinSize is specified, the sum of weights
 is multiplied by the M-dimensional bin volume, (M = N(sumSet)),
 making the return value the integral over the function
 represented by this histogram

 Return the sum of the weights of a multi-dimensional slice of the histogram
 by summing only over the dimensions specified in sumSet.

 The coordinates of all other dimensions are fixed to those given in sliceSet

 If correctForBinSize is specified, the sum of weights
 is multiplied by the M-dimensional bin volume, (M = N(sumSet)),
 or the fraction of it that falls inside the range rangeName,
 making the return value the integral over the function
 represented by this histogram

 If correctForBinSize is not specified, the weights are multiplied by the
 fraction of the bin volume that falls inside the range, i.e. a factor or
 binVolumeInRange/totalBinVolume.

 Fill the transient cache with partial bin volumes with up-to-date
 values for the partial volume specified by observables 'dimSet'

 Return the number of bins

 Return the sum of weights in all entries matching cutSpec (if specified)
 and in named range cutRange (if specified)
 Return the

 Reset all bin weights to zero

 Return an argset with the bin center coordinates for
 bin sequential number 'masterIdx'. For iterative use.

 Return a RooArgSet with center coordinates of the bin
 enclosing the point 'coord'

 Return the volume of the bin enclosing coordinates 'coord'

 Set all the event weight of all bins to the specified value

 Create an iterator over all bins in a slice defined by the subset of observables
 listed in sliceArg. The position of the slice is given by otherArgs

 Change the name of the RooDataHist

 Change the title of this RooDataHist

 Print value of the dataset, i.e. the sum of weights contained in the dataset

 Print argument of dataset, i.e. the observable names

 Cache the datahist entries with bin centers that are inside/outside the
 current observable definitio

 Return true if currently loaded coordinate is considered valid within
 the current range definitions of all observables

 Returns true if datasets contains entries with a non-integer weight

 Print the details on the dataset contents

 Stream an object of class RooDataHist.

 Return empty clone of this RooDataHist

 Add one ore more rows of data

 Return set with coordinates of center of current bin

 Return true as all histograms have in principle events weight != 1

 Return weight of current bin