[tex-eplain] boldface greek symbols

[Gérald Tenenbaum]

Thanks.
I did not find bold Greek in any of the listed packages. It would be 
useful to have one at hand.
Regards,

Gérald

Karl Berry a écrit le 27/8/23 à 23:18 :
> (Well, Dan just wrote a reply with real examples along these lines, but
> I'll send this anyway FWIW.)
>
> First, I suspect that existing plain TeX font packages (there are quite
> a few) have already solved this. For instance, this one:
> https://www.ctan.org/pkg/font-change
>
> General topic with more: https://www.ctan.org/topic/plain-ext
> (I haven't actually tried working with any of them.)
>
>
> I believe the issue with the bold math italic "sometimes" working is
> plain.tex's math character definitions. In order to have \alpha, ...,
> \omega, \vartheta, etc., respect \fam, their defns need to be changed to
> have class 7 (variable) instead of 0 (ordinary). For instance, plain.tex
> says: \mathchardef\vartheta="0123
>
> That initial 0 means an ordinary symbol, and \fam does not apply.
> Compare with \Delta:
> \mathchardef\Delta="7001
>
> The 7 means the symbol follows \fam. You can read more about this in
> The TeXbook, or no doubt any other reasonable plain TeX book. (I expect
> that Victor covers it in gory detail in TeX by Topic.)
>
> Here's what Knuth says about bold math italic specifically (it's the
> exercise at the top of page 156, if you have the book):
>
>      Assume that the control sequence
>      |\bmit| has been defined as an abbreviation for `|\fam=9|'; hence
>      `|{\bmit b}|' will give a boldface math italic~|b|. What change to the
>      definition of\/ |\alpha| will make |{\bmit\alpha}| produce a
>      boldface~alpha?
>
>      \answer |\mathchardef\alpha="710B|. Incidentally, |{\rm\alpha}| will
>      then give a spurious result, because character position \hex{0B} of
>      roman fonts does not contain an alpha; you should warn
>      your users about what characters they are allowed to type under the
>      influence of special conventions like ^|\rm|.
>
> I can't undertake the research, or implement a solution, though.  Sorry.
> --hope this helps somehow, karl.
>

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