Re: Special Excel-meaning of median.

[Morten Welinder <terra diku dk>]

Oh, boy.

In *my* book, the median (singular) and any other fractile is an
observation in the data set.  More precisely, it is the largest
of the medians (plural).  If the destribution function is called
F, the medians are the members of the set

    { x | lim [xm -> x-] F(xm) <= p <= F(x) }

where, p=1/2.  (That would be the closed interval between the two
points that Excel average over in the discrete case.)

But we're shooting for Excel compatibility, so all that is not
very important.


> In any case, it would be nice to use this function in analysis-tools.c. 
> That's why I am wondering whether this function shouldn't be in 
> math-func.h/c with all the other range_* functions rather than in 
> fn-stats.c?

I think it may be time to extract all the range functions (none of
which are related to R code, btw.) out into a new file, say rangefuncs.c.
That would make them callable from analysis-tools.c

Morten