Newsgroups: comp.text
Path: utzoo!utgpu!news-server.csri.toronto.edu!torsqnt!lsuc!robohack!eci386!woods
From: woods@eci386.uucp (Greg A. Woods)
Subject: Re: In troff, is "|" supposed to be slanted in Italic?
Message-ID: <1991May8.190648.3769@eci386.uucp>
Reply-To: woods@eci386.UUCP (Greg A. Woods)
Organization: Elegant Communications Inc.
References: <1470@ecicrl.ocunix.on.ca> <1991May6.152022.28260@cbnewsl.att.com>
Date: Wed, 8 May 1991 19:06:48 GMT

In article <1991May6.152022.28260@cbnewsl.att.com> npn@cbnewsl.att.com (nils-peter.nelson) writes:
> In fixing up xditview, this was the one "bug" I couldn't
> solve. eqn | troff | xtv     will display piles with
> slanted lines. Brian Kernighan (author of pic) insists
> italic applies to letters only; X persistently slants
> *all* characters in the Italic fonts. Brian says he may
> try to change pic not to assume Italic is safe for
> non-letters, but no promises.

I'd tend to say Brian is right, and someone is using an old eqn.

I've been waiting for Chris Lewis to reply, but the question has been
nagging me too much.

The output Chris submitted in the original posting came from a V7
derived eqn.  I tried the same test with DWB-1.0, DWB-2.0, and
SQPS-2.9 (derived from DWB-2.0).

DWB-1.0 shows the same behaviour Chris noted, with almost the exact
same output from eqn.

DWB-2.0 shows an entirely different handling of fonts in eqn, much
like what Nils-Peter says BWK claims.  In addition, output appears
correct when processed both by tpscript and xproof (on a DMD).

SQPS-2.9 is also correct, and its sqeqn output is also almost
identical to that of DWB-2.0.

So, my nagging question -- Has DWB-3.1 slipped back to the V7/DWB-1.0
version of eqn?  If so, how/why?  Does DWB-3.2 fix this?

> I had to put shameful fudges in to get square roots,
> table corners and brackets to align, because of
> similar disagreements between X, PostScriptt and troff.

Ah, the age-old problem of finding symbol characters in your favourite
output device that have the same positioning and size as what troff
expects.  My favourite gripe is that troff (from DWB-2.0) uses \(ru to
draw horizontal lines (i.e. \l'1.0i'), instead of whatever drawing
mechanism that may be implemented to draw every other line.  To top it
off, most of the lines in tbl are also drawn with characters.  At
least sqtroff-2.9 draws horizontal lines with the line drawing
mechanism, though sqtbl might still use characters.

Of course if you are using some form of PostScript device, or other
device that allows custom definition of characters, it's (almost) easy
enough to fudge up some special characters to meet troff's specs.

BTW, I've almost fixed up the definition of \(br and \(ru in
PostScript for tpscript.  There's still a very minor positioning
problem, and a line-thickness problem, but at least now \(ru looks
similar to the other lines.
-- 
							Greg A. Woods
woods@{eci386,gate,robohack,ontmoh,tmsoft}.UUCP		ECI and UniForum Canada
+1-416-443-1734 [h]  +1-416-595-5425 [w]  VE3TCP	Toronto, Ontario CANADA
Political speech and writing are largely the defense of the indefensible-ORWELL