Re: [Phys-L] a/(b/c)

[John Denker <jsd@av8n.com>]

On 2/5/19 6:40 AM, Jeffrey Schnick wrote:

> Okay here's another notation question.  For a/(b/c), (where a, b, and
> c are scalars) I've been seeing:
>
>  a
> ------
>  b
>   --
>  c
>
> In other words, students use the length of the horizontal rule to
> indicate the order of operations.  I haven't been letting that one
> slide.  Any thoughts on that one?

Three answers:

1) Sometimes the length-cue is 100% proper and necessary, e.g.
 in continued fractions.  https://en.wikipedia.org/wiki/Continued_fraction

2) Sometimes it's a matter of taste.  Speaking for myself,
 I usually prefer something like

	  a
	-----
	b / c

 i.e. using a diagonal slash when possible.  This is more
 familiar and therefore easier on readers.  It's unambiguous.

3) As the saying goes, no matter what you are doing, you can
 always do it wrong.  There are lots of ways to typeset a
 formula so as to make it incomprehensible.

----------------------

Once upon a time, when I was in grad school, I had a TA job
that involved grading papers.  I saw one paper that was
utterly incomprehensible, even though the bottom-line result
was numerically correct.  Since "show the work" was part of
the assignment, and since there was no reason to believe the
student knew what was going on, I took off lots of points.

The student, in tears, came to my office.  She explained her
notation.  It was wrong by any traditional or objective standard,
almost but not entirely crazy.  I gave her full credit, on the
grounds that she did understand the physics.  Then I explained
the advantages of standard notation.  I felt terrible about this,
and still do.  I learned my lesson.  Now I almost never take off
points for "creative" notation.  Instead, I respect the distinction
between grading papers and /correcting/ papers.  That is, I write
the preferred notation on the paper, without taking off any points.
In 99% of the cases they take the hint.

De gustibus minime disputandum.

That is, I argue questions of taste as gently as possible.

(If I were teaching an upper-division course for math majors I
would play by different rules.)