For a brob
object, being NA
is not entirely
straightforward. The S4 method for is.na
is too
“strict” for some of the functions considered here. Consider
max(a)
where a
includes only positive, fully
specified, elements, and elements with known negative sign and
exponents that include NA
values. Here, max(a)
is unambiguously determined.
Similar logic applies to min()
and, by extension,
range()
.