Upside down E was Re: Mathematical Symbols

[James A. Landau]

In a message dated 2/20/03 11:02:36 AM Eastern Standard Time,
JMB at STRADLEY.COM writes:

>         After writing the previous message, I realized that I'm uncertain
> which axis is considered "vertical."  I was referring, perhaps wrongly, to
> the z-axis, not the y-axis.

This may surprise you, but there is no universal convention as to which axis
of a three-dimensional coordinate system is vertical.

My personal preference is for x axis to the right, y vertical, and z sticking
out of the page (that is, the x and y as in 2-dimensional graphs, with the z
added), but it is perhaps more common to see x to the right, z vertical, and
y sticking out of the page.  Just to check, I picked up a reference book and
found y was horizontal, z was vertical, and x stuck out of the page.

I remember once for a college homework assignment folding the page on which
my answer was written so that the prof could see which way my coordinates ran.

As for "upside down", yes it makes sense to see you turn something upside
down by rotating it on the roll axis, that is, by leaving it flat on the
desktop while rotating it 180 degrees.  If you do so to the capital F, you
get the bars sticking out to the left.  However, what term would you then use
to describe a capital F turned in such a way that the long horizontal bar was
on the bottom and sticking out to the right?

       - Jim Landau