[texhax] undertilde and MiKTeX

[Jerry]

On Sat, 28 Oct 2017 10:05:51 +1300, Rolf Turner stated:

>The journal of which I am Technical Editor provides a document class 
>file which implements the style conventions that papers published in the
>journal must meet.
>
>This document class makes use of the "\undertilde" command.  Apparently 
>there are licensing issues with the undertilde package, and for this 
>reason (I think) my installation of texlive has no undertilde.sty file,
>but rather a file undertilde.tex.  Explicitly:
>
>  /usr/share/texlive/texmf-dist/tex/generic/genmisc/undertilde.tex
>
>For *that* reason the document class file for the journal uses
>
>     \input{undertilde}
>
>rather than
>
>     \usepackage{undertilde}
>
>An author contacted me just now saying that he is getting an error
>
>     > File `undertilde.tex' not found. \input{undertilde}  
>
>This author is using TeXstudio which is a front end for MiKTeX.
>
>I have difficulty investigating this problem, since I
>*don't do Windoze* !!!  However some Googling indicates that MiKTeX 
>should indeed have access to undertilde.
>
>The curly is that one Google hit appears to indicate that MiKTeX 
>possesses undertilde.sty and another that it possesses undertilde.tex.
>These files would appear to live in
>
>    ...\texmf\tex\generic\genmisc
>
>(a) Can someone who uses Windoze/MiKTeX please confirm whether either or 
>both of the files undertilde.sty and undertilde.tex are present?  Where 
>they should be?

Both are present.

C:\Program Files\MiKTeX 2.9\tex\generic\genmisc\undertilde.tex
C:\Program Files\MiKTeX 2.9\tex\latex\undertilde\undertilde.sty

>(b) It strikes me that it is possible that some releases of MiKTeX have
>undertilde.sty and some (older ones perhaps?) have undertilde.tex.
>
>If this is indeed the case I would like to be able to construct a 
>conditional input something along the lines of:
>
>   if(the file undertilde.sty is found) {
>       \usepackage{undertilde}
>   } else if(the file undertilde.tex is found) {
>       \input{undertilde}
>   } else {
>       Bail out with a message "undertilde not available"
>   }
>
>Can some clever person instruct me (monosyllabically; I'm a Bear of Very 
>Little Brain) as to how to construct such a conditional?
>
>Eternally grateful.
>
>cheers,
>
>Rolf Turner

-- 
Jerry