Imprecise font scaling

[Alexander Slávik]

Hello,

I'm running the following code

\version "2.25.12"
\markup { LOL }
\markup { \magnify #2.0 LOL }

and the results are not really precise. When producing --eps, the relevant 
output lines are

/C059-Roman 3.86523438 output-scale div selectfont
/C059-Roman 7.73242188 output-scale div selectfont

However, 2 * 3.86523438 = 7.73046876 != 7.73242188. Basically the same 
behaviour can be
observed when using Cairo (both for EPS and SVG). (Producing SVG without Cairo 
is pretty
disastrous in this regard, but that doesn't bother me too much at the moment.)

You might say that the differences are negligible; and perhaps you're right. On 
the other
hand, I'd be alarmed if my code produced such a "big" difference when a simple 
multiplication
by two is expected.

By the way, my initial motivation was to find out what the output font sizes 
*really* are
(especially with respect to the lyrics) so that I can include LilyPond examples 
in TeX
with *exactly* the same font (size). I couldn't locate any documentation for 
these
mechanisms so far…

Best,
AS