bug#43902: 28.0.50; Calc: Wrong eval precedence rules with LaTeX language

[Mattias Engdegård]

Michael Heerdegen dixit:

> M-x calc RET
> d L                   ;; calc-latex-language
>  '                    ;; calc-algebraic-entry
> 1+1/2 RET
> 
> The result is 1, and the Trail shows alg' (1 + 1) / 2.  It does not make
> much sense to me to use a precedence rule where addition has higher
> precedence than division.  I know LaTeX a bit and don't expect such a
> result, and it doesn't seem to be documented.  Is it intended or a bug?


Indeed, $a+b/c$ is typeset by (La)TeX as (approx.) a + b/c which can only mean 
one thing, but Calc incorrectly parses it as (a+b)/c. This seems to be the 
consequence of an explicit change:

  commit fda9b316f84dbc6d68e6cb74b386ee4b92d81b31
  Author: Jay Belanger <jay.p.belanger@gmail.com>
  Date:   Fri Nov 16 04:15:23 2007 +0000

    (math-oper-table): Fix typo.  Reduce precedence of "/" for TeX.

  --- a/lisp/calc/calc-lang.el
  +++ b/lisp/calc/calc-lang.el
  -     ( "/"       /                185 186 )
  +     ( "/"       /                170 171 )

Jay, do you remember the reason for this change?