https://math.stackexchange.com/questions/1596022/difference-between-real-functions-and-real-valued-functions
It's not a matter of
line continuity xor field continuity:
it's a matter of
line continuity and field continuity.
Interesting properties of this
first bridge between the discrete and continuous
include for example that it's a CDF and "a"
(surprisingly enough not "the") pdf of the
natural integers at uniform random,
surprising because otherwise we know that
probability distributions are defined by a
unique pdf.
So, this example (and you'll notice counterexample
to uncountability and otherwise no bridge between
discrete and continuous) has other usual unique
properties as among our combined constructions and
here in reference to otherwise the uniqueness up
to isomorphism of the complete ordered field and
otherwise the sufficiency of Dedekind-completeness.
(Or "Eudoxus/Dedekind/Cauchy is insufficient", not
so much for what it shows, but for what it doesn't
show here in terms of the bridge between
discrete and continuous.)
So, then why scientists and engineers might find
any extra utility in this result that what there
is of the analytical character of the reals as
courtesy countable additivity, then is about the
aspects of points in or on a line then in higher
dimensions, and about how points are two-sided on
the line then 3/4/5 sided on the plane, etc, then
about for example Banach-Tarski, Vitali, and, the
re-Vitali-ization of measure theory.
Establishing the IVT (for the FTC's) is one thing,
here there's also _more_ about the numbers from
this approach, where uncountability becomes
expressly mute about what would contradict itself
in terms of the perfect results of the analytical
character of the reals and countable additivity.
There's a quote from the mathematical appendices to
R. Penrose's "Fashion, Faith, and Fantasy in the
New Physics of the Universe" (2016) that I wanted
to share with you.
"Cantor's theory of (cardinal) infinities is really
concerned just with _sets_, which are not thought of
as being structured as some kind of continuous space.
For our purposes here, we do need to take into
account continuity (or smoothness) aspects of the
spaces that we are concerned with."
This is following:
"I mention Cantor's theory here only so as to
make the contrast with what we are doing here,
which is different."