TNDArray
N-Dim array class.
Storage layout:
Assume 3 dimensions, array sizes 2, 4 and 3 i.e. 24 bins:
Data is stored as [0,0,0], [0,0,1], [0,0,2], [0,1,0],...
fSizes stores the combined size of each bin in a dimension, i.e. in
above example it would contain 24, 12, 3, 1.
Storage is allocated lazily, only when data is written to the array.
TNDArrayRef gives access to a sub-dimension, e.g. arr[0][1] in above
three-dimensional example, up to an element with conversion operator
to double: double value = arr[0][1][2];
This class is also known as (typedefs to this class)
TNDArrayRef<
Double_t>