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diff --git a/info/ltx3pub/l3d002g.tex b/info/ltx3pub/l3d002g.tex new file mode 100644 index 0000000000..de36a7d302 --- /dev/null +++ b/info/ltx3pub/l3d002g.tex @@ -0,0 +1,484 @@ +%%% ==================================================================== +%%% @LaTeX3-article{ LaTeX3-LTX3-002a, +%%% filename = "l3d002a.tex", +%%% archived = "ctan:/tex-archive/info/ltx3pub/", +%%% related-files = "part of l3d002.tex", +%%% author = "David Rhead", +%%% doc-group = "Project core team", +%%% title = "Some ideas for improving {\LaTeX}\\ General", +%%% version = "1.1", +%%% date = "18-Mar-1993", +%%% time = "20:19:36 GMT", +%%% status = "public, official", +%%% abstract = "Ideas and suggestions from David Rhead for +%%% improving various areas in LaTeX", +%%% note = "prepared for the workshop at Dedham 91", +%%% keywords = "", +%%% project-address = "LaTeX3 Project \\ +%%% c/o Dr. Chris Rowley \\ +%%% The Open University \\ +%%% Parsifal College \\ +%%% Finchley Road \\ +%%% London NW3 7BG, England, UK", +%%% project-tel = "+44 171 794 0575", +%%% project-FAX = "+44 171 433 6196", +%%% project-email = "LTX3-Mgr@SHSU.edu", +%%% copyright = "Copyright (C) 1993 LaTeX3 Project +%%% All rights reserved. +%%% +%%% Permission is granted to make and distribute +%%% verbatim copies of this publication or of +%%% coherent parts from this publication provided +%%% this copyright notice and this permission +%%% notice are preserved on all copies. +%%% +%%% Permission is granted to copy and distribute +%%% translations of this publication or of +%%% individual items from this publication into +%%% another language provided that the translation +%%% is approved by the original copyright holders. +%%% +%%% No other permissions to copy or distribute this +%%% publication in any form are granted and in +%%% particular no permission to copy parts of it +%%% in such a way as to materially change its +%%% meaning.", +%%% generalinfo = "To subscribe to the LaTeX3 discussion list: +%%% +%%% Send mail to listserv@vm.urz.uni-heidelberg.de +%%% with the following line as the body of the +%%% message (substituting your own name): +%%% +%%% subscribe LaTeX-L First-name Surname +%%% +%%% To find out about volunteer work: +%%% +%%% look at the document vol-task.tex which can +%%% be obtained electronically, see below. +%%% +%%% To retrieve project publications electronically: +%%% +%%% Project publications are available for +%%% retrieval by anonymous ftp from ctan hosts: +%%% ftp.tex.ac.uk +%%% ftp.dante.de +%%% ftp.shsu.edu +%%% in the directory /tex-archive/info/ltx3pub. +%%% +%%% The file ltx3pub.bib in that directory gives +%%% full bibliographical information including +%%% abstracts in BibTeX format. A brief history +%%% of the project and a description of its aims +%%% is contained in l3d001.tex. +%%% +%%% If you only have access to email, and not ftp +%%% You may use the ftpmail service. +%%% Send a message just containg the word +%%% help +%%% to ftpmail@ftp.shsu.edu +%%% for more information about this service. +%%% +%%% For offers of financial contributions or +%%% contributions of computing equipment or +%%% software, contact the project at the above +%%% address, or the TeX Users Group. +%%% +%%% For offers of technical assistance, contact the +%%% project at the above address. +%%% +%%% For technical enquiries and suggestions, send +%%% e-mail to the latex-l list or contact the +%%% project at the above address.", +%%% checksum = "55562 484 2612 20025", +%%% docstring = "The checksum field above contains a CRC-16 +%%% checksum as the first value, followed by the +%%% equivalent of the standard UNIX wc (word +%%% count) utility output of lines, words, and +%%% characters. This is produced by Robert +%%% Solovay's checksum utility.", +%%% } +%%% ==================================================================== + +\chapter{Could \LaTeX\ do more for chemists?} + +This appendix is based on a \lq\lq paper'' that I e-mailed a while +back. It also contains some e-mailed comments. + + +\section{Motivation} + +\begin{footnotesize}\begin{verbatim} +From: Rainer Schoepf <Schoepf@DE.DBP.ZIB-BERLIN.SC> +Date: Mon, 15 Oct 90 13:09:23 +0100 + +I got the following message a while ago, as a reaction to a discussion +I had with John Simmie after the talk at Cork. He's a chemist, so his +focus of interest is different from the mathematicians one. I think it's +interesting to pass this on to the list. + + - Rainer + +----------------------original message follows ------------------------------ + +... I would like to see ... +a user-definable environment which would parallel displaymath-mode. + +For example, in printing chemical equations the conventions are that +the text is in roman not math-italic---ok this is easily done via +\def\chem{\rm\everymath={\rm}} +and \chem can now be included inside $...$ or \[ ... \] or $$ ... $$ etc +or outside as for {\chem\begin{eqnarray} ... \end{eqnarray}} +Your virtual fonts approach will also work. +Problems arise if mathematical and chemical equations are mixed in the sense +text +text +\begin{equation} pV = nRT \end{equation} +text +\begin{equation}\chem + 2 H_2 + 2O_2 = 2H_2O \end{equation} +text +because the automatic numbering schemes assigns (1) to the first eqn +and (2) to the second. Whereas one wants to number maths eqns and +chemical eqns (reactions) independently---for example, +(2.1) eqn 1 of chapter 2 and (1) reaction number 1, maybe in bold or +oldstyle and maybe with <> brackets. + +At the moment the only solution is to hack into latex.tex +and duplicate LL's \equation and \eqnarray environments with new +counters and parameters---this I have done and it works fine for +simple examples but failed for cases where the number of stacked +eqnarray's exceeded the page size (hash size and other mysterious errors). + +You suggested that AMSTEX might do but on reflection that involves +even more maths---and what us chemists want is less! + +Another feature is the lack of a construct to do the following: + + catalyst + 2H_ + O_2 -------------> 2 H_2O + 300 K; 4 bar +where the length of the arrow (---> or <--- or <===>) is +determined by the amount of text over and under it. + +Note that we do not want to disable the equation environment just +have a second customisable one. + +Regards, John. +\end{verbatim}\end{footnotesize} + +\section{Typesetting and artwork} + +It may help to consider the division of labour +within a traditional publishing house. A ``copy-editor'' +\cite[p.\ 236]{butcher-81} might divide the +work on chemical formulae up between ``the printer'' and ``the draughtsman''. +Thus, some formulae can be typeset, but others are treated as ``artwork'' +and are drawn. + +Although there have been valiant attempts \cite{haas+okane,ramek-90} +to define \TeX\ macros for +drawing chemical structure diagrams, +I think it is inevitable that, whatever \TeX\ macros +are defined, there will be chemists who come along with requirements that +are beyond the abilities of the macro packages. Therefore, it seems sensible +to retain the traditional division between typesetting and artwork: to +typeset those formulae that can be typeset easily and to get the other +formulae drawn in some way. + +In \TeX\ terms, artwork can be treated as ``graphics'' to be +``pasted'' into a typeset document via \verb+\special+. +For example, +{\sc chemdraw} +\cite{CSC} can produce ``encapsulated {\sc PostScript}'', +so a \LaTeX-ed document with {\sc chemdraw} diagrams can be printed on +a {\sc PostScript} printer. + +\section{Desirable facilities for chemists in the new \protect\LaTeX} + +\LaTeX\ is never going to be a system for producing ``artwork'', +so it seems to me that it would be unwise to attempt to provide comprehensive +facilities for ``chemical artwork'' in \LaTeX. +However, it does seem worth providing a limited number of +facilities to make it easier to produce the chemical +formulae that should be treated as ``typesetting''. + +\subsection{Environments} + +Chemists' problems start when they use \LaTeX's ``mathematics'' +environments for ``chemistry''. Chemistry is not mathematics, and +the conventions for typesetting chemistry are different from those for +typesetting mathematics. In terms of the \LaTeX\ philosophy +\cite[p.\ 6]{lamport-86} +``mathematics'' and ``chemistry'' represent ``logically distinct structural +elements''. + +It would seem natural to: +\begin{itemize} +\item define environments for chemists that are + analogous to the environments that are available for mathematicians +\item within these ``chemistry'' environments, aim to keep to + whatever typesetting conventions are usual in chemistry. +\end{itemize} +How about defining {\tt chem}, {\tt displaychem} and {\tt chemequation} environments, +by analogy with {\tt math}, {\tt displaymath} and {\tt equation}? + +If such environments were defined, the style-file writer would then +have control over ``mathematics'' and ``chemistry'' separately. +In particular: +\begin{itemize} +\item The default would be \verb+\rm+ for chemistry (although + a designer could change the default in a {\tt .sty} file). + Individual + authors would no longer have to search through + ``double bend'' sections of the \TeX book themselves + \cite[pp.\ 163 \& 179]{knuth-90}. +\item A designer could implement a house-style in which + mathematical and chemical equations are numbered in separate + sequences + \cite[p.\ 224]{butcher-81} or a house-style in which there is only one + sequence of numbers \cite[p.\ 132]{dodd-86}. +\item It might be possible to arrange that subscripts will normally be + at the same level \cite[p.\ 179]{knuth-90} inside the environments + for chemistry. +\end{itemize} + +\subsection{Commands} + +At first sight, the \LaTeX\ manual \cite[ch.\ 3]{lamport-86} gives +the impression that \LaTeX\ 2.09 provides the +``building blocks'' to give all the arrows, harpoons and annotation that +a chemist could want. However, it is often difficult to get these +building blocks arranged in the ways required. +For example: +\begin{itemize} +\item How does one obtain CH${_3}$(C=O)OCl + \cite[p.\ 235]{butcher-81} in ``math mode''? + We can't simply + use ``='' + to mean ``double bond'', since \TeX\ puts space + around it. +\item To represent a reversible reaction with rate constants above/below + a pair of harpoons, I ended up with + \begin{verbatim} + \[ + \renewcommand{\arraystretch}{0.5} + A \begin{array}{c} + \scriptstyle k\_1 \\ [1mm] + \rightleftharpoons \\ + \scriptstyle k\_{-1} + \end{array} B + \] + \end{verbatim} + before it looked right. Surely individual \LaTeX\ users shouldn't have + to re-do the ``tuning'' needed to get these things right? +\item As in the above example, + arrows and harpoons are often labelled to show reaction conditions. + It is not clear how to get arrows/harpoons that expand to the + width of the labels. +\end{itemize} +Many of these difficulties are another consequence of trying to use, +for chemistry, +the structural elements that were designed for mathematics. + +So what commands might usefully be made available inside some future +``chemistry'' environments? +\begin{itemize} +\item +It seems desirable \cite[p.\ 237]{butcher-81} +to have documented facilities for +single and double bonds. Triple bonds might also be needed +\cite{chemsoc-61}. +Documented facilities would also be useful for representing +\begin{itemize} +\item single bonds by raised dots \cite[p.\ 59]{hart-83} +\item ``association of an unspecified type'' by three centred dots + \cite[p.\ 96]{dodd-86}. +\end{itemize} + +Might commands such as \\ +\verb+\bond+, \verb+\doublebond+, +\verb+\triplebond+ and \verb+\association+ \\ +be appropriate? +\item +It seems desirable to have specific commands for arrows/harpoons +with labels above/below (to indicate conditions or rate +constants). We can obtain an indication of the combinations +of arrows/harpoons that might have traditionally been typeset from +\cite[p.\ 371]{chicago-82}. +Thus, as well as providing simple arrows for one-way reactions, it might +be worth aiming to provide commands for: equilibrium reactions (beginning +at left and right); reversible reactions (beginning at left and right); +reactions beginning at left/right and completed to left/right. +Might it be worth defining some commands such as \\ +\verb+\oneway+, +\verb+\equilibriumR+, +\verb+\equilibriumL+, +\verb+\reversibleR+, \\ +\verb+\reversibleL+, +\verb+\rightright+, +\verb+\rightleft+, +\verb+\leftright+, +\verb+\leftleft+, \\ +that each accept two parameters: one to give a label +above the symbol, the other to give a label below the symbol? +For example, + +\begin{footnotesize}\begin{verbatim} +\begin{displaychem} + 2H\_2 + O\_2 \oneway{catalyst}{300 K; 4 bar} 2 H\_2O +\end{displaychem} +\end{verbatim}\end{footnotesize} + +might be a natural way to specify +\marginpar{\it But oneway, etc.\ + should ensure that symbol width exceeds label width} +\[ \rm +2H_2 + O_2 + \renewcommand{\arraystretch}{0.5} + \begin{array}{c} + \scriptstyle\rm catalyst \\ [1mm] + \longrightarrow \\ + \scriptstyle\rm 300\ K;\ 4\ bar + \end{array} + 2H_2O +\] +\end{itemize} + +\section{Work involved} + +I'd guess that my suggestions about environments could be implemented +by slight modications of the code that implements the corresponding +environments for mathematics. + +Some new work would be required for commands such as +\verb+\bond+, \dots~, \verb+\association+, +\verb+\oneway+, \dots~, \verb+\leftleft+. (The only facility +like \verb+\oneway+, \dots~, \verb+\leftleft+ +that I've found +in an existing macro package is that for arrows in \AmSTeX\ +\cite[p.\ 140]{spivak-86} +but, from a chemist's point-of-view, this doesn't provide sufficient +choice of symbols.) + +It might be worth seeking advice about objectives +from people who typeset chemistry professionally. +% Perhaps the UK's Royal Society of Chemistry would be prepared to advise +% about details. I've been in e-mail correspondence with their Publications +% Manager about authors submitting manuscripts electronically to them, +% although they seem to be going the wordprocessor + chemdraw + SGML route. + +\section{Documentation} + +If the facilities that I've outlined above were provided, I would +be inclined to give them less prominence in the documentation than +the analogous facilities for mathematicians. This would help +give the impression that, whereas mathematicians can expect \LaTeX\ +to do everything they want, chemists can only expect \LaTeX\ to do a certain +proportion of what they want. +For example, in the successor to \cite{lamport-86}, +the description of facilities for +chemists might be relegated to an appendix, which could start with a +paragraph explaining that the facilities are intended to support ``typesetting'' +but not ``artwork''. + +\section{Some e-mail comments} + +\begin{footnotesize}\begin{verbatim} +From: CA_ROWLEY@UK.AC.OPEN.ACS.VAX +Date: Mon, 22 Oct 90 13:51:21 GMT + +This is a comment on the message from John Simmie, passed on by Rainer: + +Whilst I think that the typesetting of chemical formulas, etc, is an +important area for any TeX-based system to provide. I think that, in +common with maths, it should be provided by an add-on package (as +AMS-LaTeX does for maths). This should be written in close +cooperation with experts in such typesetting. + +Nevertheless, we should attempt to ensure that we dot make any +decisions about "basic LaTeX" which make such an add-on dificult to +produce. It is not clear to me how we can achieve this in general +(since it applies to many other specialist areas of typeseting) +but I cannot see anything in John's requests that requires any changes +to basic LaTeX. +\end{verbatim}\end{footnotesize} +\begin{center} --- \end{center} +\begin{footnotesize}\begin{verbatim} +From: David Rhead ... +Date: 24 Oct 90 14:10:44 + +% A LaTeX input file +\documentstyle[11pt]{article} + + +\begin{document} + +% A chemist might hope to typeset single/double/triple bonds in +% the following "obvious" ways. However, none of them will give +% what is required (because, although the bonds are visually +% similar to some mathematical sybols, they are logically different). + +A single bond? $X-Y$ + +A single bond? $X.Y$ + +A single bond? $X\cdot Y$ + +A double bond? $X=Y$ + +A triple bond? $X\equiv Y$ + +\end{document} +\end{verbatim}\end{footnotesize} +\begin{center} --- \end{center} +\begin{footnotesize}\begin{verbatim} +Subject: Re: Facilities for chemists. A LaTeX example file. +From: bbeeton <BNB@COM.AMS.MATH> +Date: Wed, 24 Oct 90 18:14:13 CET + + +in looking at david rhead's chemistry example, i find two distinct +notions presented: + (a) "the bonds are visually similar to some mathematical symbols" +and + (b) "they are logically different" + +why is it necessary to use the existing notation, just because of (a)? +why isn't it possible, yea almost trivial!, to define new names and +structures for these that are logically distinct? tex, after all, is +a powerful macro language -- one of its main, perhaps most important, +selling points. + +i offer another example to illustrate what i'm suggesting. + $\vector a$ (or $\vector{a}$ ) +assume this will be used only in math mode. +if you're a mathematician this becomes + \def\vector#1{\vec{#1}} +if you're a physicist, it becomes + \def\vector#1{{\bf#1}} +here the logical notion is the same, but the representation is different. + +seems to me that this is what sgml is trying to tell us. teach the +user to capture the logic, and let the representation be taken care of +behind the scenes. + +i don't say that the available fonts and structures are adequate for +chemistry (they're almost certainly not), but that doesn't mean that +suitable new ones can't be constructed. +\end{verbatim}\end{footnotesize} +\begin{center} --- \end{center} +\begin{footnotesize}\begin{verbatim} +From: David Rhead ... +Date: 25 Oct 90 14:08:11 + +... + +... with reference to Barbara's message, there may be no difference +between what she's suggesting and what I'm suggesting. ... +... I just intended +to show what a chemist might actually do on seeing the current LaTeX +manual (before the chemist found that it didn't give him/her what s/he +wanted), not to show what I think chemists should do in future. +I agree with Barbara that, in an ideal world (to which we are working with +LaTeX 3.0), the user should not use the existing notation ... +\end{verbatim}\end{footnotesize} |