[Fontinst] fontinst fontdsize variance?

Karl Berry karl at freefriends.org
Mon Feb 8 19:51:13 CET 2016

Hi Lars,

    This smells like a rounding issue, does it not?

Yes, it sure does.  It just seemed bizarre to me the TFM would store
more digits than could be used by TeX.  But I guess it does.

      - the TFM format keeps more than 16 bits after the decimal point in the 
    designsize (not sure how many; would need to check the format spec to be 
    sure) which is of questionable value,

Yeah.  It's a fix_word: 32 bits, 12 to the left of the binary point.
(See, e.g., section 541 in tex.web, "The most important data type used

      - the EC fonts have botched the design size calculation for its 14pt-ish 
    size (it's supposed to be 14.4pt exactly).

Yeah.  Haven't looked at the EC sources in decades, and not going to :).
Maybe it's related to the "improved" precision of the EC font names.
Well, in any case, they aren't going to change now.

    fontinst side do anything to avoid them completely? I think so (but
    whether it is worth it is another matter).

The reason why it could be worth it is that I have scripts to check vf
validity in TL that are run regularly.  Of course I can tell the scripts
not to check these particular fonts, but then any real errors, like
unresolved base fonts (this happens sadly frequently, overall) would be

I guess I could tweak my scripts to ignore only that particular error,
within some tolerance.  (Real design size variance has happened too,
usually indicating the "wrong" base font was used.)  Maybe that is the
simplest solution.

    from a cursory glance this looks perfectly doable.

Well, if you're up for it, that would be fantastic :).

Thanks either way.  -k

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