[cfp-interest 3939] fdim() and deferring to history

[Damian McGuckin]

So as to preserve the reason for a name,

 	determine the positive difference between

to
 	determine the positive difference between, long ago called "the
 	diminishing" of, its arguments

By long, I mean mid 1950s and the routine's introduction in Fortran II.

At least that will stop stupid questions as to why this name is what it is

Thanks - Damian