BoundingBox in PostScript output for A4 is too large and the computation with its comment are bogus
Reinhard Kotucha
reinhard.kotucha at gmx.de
Mon Mar 11 06:45:59 CET 2024
On 2024-03-10 at 04:45:51 +0000, Al Ma wrote:
>> I think that it's quite useful to provide a HiResBoundingBox
>> comment as well. The latter allows real numbers instead of
>> integers.
> Almost no reals can be spelt out. Do you probably mean the
> rationals or the rationals representable in decimal notation?
> Notice that the width of A4 is 21 cm / (2,54 cm/in) × 72 pt/in =
> 75600/127 pt, which cannot be represented exactly using the decimal
> notation.
It's not necessary to provide exact values. Assume that that 1 bp is
about 0.35 mm. With three decimal digits the resolution is 350 nm,
the wavelength of visible light. The resolution of a phototypesetter
(2540 dpi) is 10 𝜇m.
There is absolutely no need to express 75600/127 with more than 3 or 4
decimal digits. Even then additional rounding errors will be
introduced by successive processing steps. But three or four decimal
digits are better than none.
Regards,
Reinhard
--
------------------------------------------------------------------
Reinhard Kotucha Phone: +49-511-3373112
Marschnerstr. 25
D-30167 Hannover mailto:reinhard.kotucha at gmx.de
------------------------------------------------------------------
More information about the tex-live
mailing list.