HISTO2 calculates histogram for multiple columns with separate bin values 
    for each data column.

 R = HISTO2(Y)
 R = HISTO2(Y, W)
	Y	data
	W	weight vector containing weights of each sample, 
		number of rows of Y and W must match.
		default W=[] indicates that each sample is weighted with 1. 

 R = HISTO(...)            
 	R is 	a struct with th fields 
       R.X  	the bin-values, bin-values are computed separately for each 
		data column, thus R.X is a matrix, each column contains the 
		the bin values of for each data column, unused elements are indicated with NaN.
		In order to have common bin values, use HISTO3.  
       R.H  is the frequency of occurence of value X 
  	R.N  are the number of valid (not NaN) samples (i.e. sum of weights)

 more histogram-based results can be obtained by HIST2RES

 see also: HISTO, HISTO2, HISTO3, HISTO4

Package: nan