[Groff] A4 paper size

[Tadziu Hoffmann]

Since there seem to be some questions/disagreements about the
size of A4 paper, here are my views on the subject:

A0 paper is defined to have an area of one square meter with
a ratio of the sides of 1:sqrt(2).  The longer side of A0 paper
is thus (using emacs as calculator)

  (sqrt (sqrt 2)) = 1.189207115002721 meters long

and that of A4 paper is 1/4 this length,

  (/ (sqrt (sqrt 2)) 4) = 0.29730177875068026 m

i.e., approx 29.73 cm.
Converting this to groff units (72000 per inch) and keeping in
mind that 1 inch = 25.4 mm, we get

  (* (/ (/ (sqrt (sqrt 2)) 4) 0.0254) 72000) = 842745.1996082276

or, rounding to an integer value,

  842745 units.

Not that this precision is really required, considering the
tolarances in paper production, misalignments in the printer,
etc., but, hey, it doesn't cost anything to use the ``best''
number.


Cheers,
Tadziu