Histogram

[maxgacode]

Hi,

The current implementation of the histogram in GSL is using, for the 
first and last bin, the rules

bin[0] corresponds to xmin <= x < xmin + d

bin[n-1] corresponds to xmin + (n -1)d <= x < xmax

and there is a comment about the last bin


***
Thus any samples which fall on the upper end of the histogram are 
excluded. If you want to include this value for the last bin you will 
need to add an extra bin to your histogram.
***

I'm facing exactly this problem. Some data are not binned in the last 
bin if the data is exactly equal to xmax. I can add an extra bin but 
this is very inconvenient especially if I'm calling 
gsl_histogram_set_ranges_uniform(), that is using the minimum and 
maximum data values, after a call to gsl_histogram_alloc().

I'm wondering why (and if it is possible to implement it) GSL is not 
using a different binning strategy like the NCAR

https://www.ncl.ucar.edu/Document/Graphics/Interfaces/gsn_histogram.shtml

The linked page has the following statement

"Note that the last interval is treated specially. This is intentional, 
to make sure that all data values that fall inclusively between the 
lowest and highest intervals are binned. "

So the last bin is filled with the rule

bin[n-1] corresponds to xmin + (n -1)d <= x <= xmax

Using this rule in the functions

gsl_histogram_increment

and

gsl_histogram_accumulate

seems (to me) much more convenient, obvious and simple. May be  it can 
be an option to be set using a function call after the histogram allocation.

Any comment welcome.

Max