[tex-k] minor errors in TeXbook Appendix G concerning genfrac

Karl Berry karl at freefriends.org
Wed Dec 12 01:02:53 CET 2018

Hi Sophie,

    1. TeXbook page A444 line 18 from the bottom mentions "let
    $(\lambda, \rho)$ be the left and right delimiters". However it
    never uses those names $\lambda$ and $\rho$ again, instead only
    mentioning the "left delimiter" and "right delimiter" in step 15e on
    page A445.

Well, they are trivially used at the end of item 15:
  The values of $\lambda$ and $\rho$ are null unless
  the fraction is ``with delims.''
But your point is taken nevertheless. I will consult.

    2. TeXbook page A445 line 13 says to replace "the generalized
    fraction by an Inner atom...". I believe this text is meant to
    instruct replacing the genfrac by an *Ord* atom.
    3. Relatedly, TeXbook page A445 line 14 (end of Rule 15e) does not
    indicate how to proceed after this processing. In contrast, Rules 1
    through 14 all end with an instruction ...

Ack, thanks. --karl.

P.S. Are you reimplementing math typesetting in some new system? Just
curious how you ended up here.

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