From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on inbox.vuxu.org X-Spam-Level: X-Spam-Status: No, score=-1.1 required=5.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FROM,HTML_MESSAGE,MAILING_LIST_MULTI autolearn=ham autolearn_force=no version=3.4.4 Received: (qmail 6305 invoked from network); 12 Jan 2022 03:45:42 -0000 Received: from minnie.tuhs.org (45.79.103.53) by inbox.vuxu.org with ESMTPUTF8; 12 Jan 2022 03:45:42 -0000 Received: by minnie.tuhs.org (Postfix, from userid 112) id EB9269D013; Wed, 12 Jan 2022 13:45:40 +1000 (AEST) Received: from minnie.tuhs.org (localhost [127.0.0.1]) by minnie.tuhs.org (Postfix) with ESMTP id CBD369CFCA; Wed, 12 Jan 2022 13:45:22 +1000 (AEST) Authentication-Results: minnie.tuhs.org; dkim=pass (2048-bit key; unprotected) header.d=gmail.com header.i=@gmail.com header.b="W32suqKV"; dkim-atps=neutral Received: by minnie.tuhs.org (Postfix, from userid 112) id DEBF39CFCA; Wed, 12 Jan 2022 13:45:20 +1000 (AEST) Received: from mail-ot1-f47.google.com (mail-ot1-f47.google.com [209.85.210.47]) by minnie.tuhs.org (Postfix) with ESMTPS id 2098B9C78F for ; Wed, 12 Jan 2022 13:45:20 +1000 (AEST) Received: by mail-ot1-f47.google.com with SMTP id t4-20020a05683022e400b00591aaf48277so1082587otc.13 for ; Tue, 11 Jan 2022 19:45:20 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=wm8GUc74DQde1SldX5v+QDGq6Ckjj0MF+TZnfV4oKTg=; b=W32suqKVSM/X6t4XGQJ0SDkgeAGDa/8gYcjHiPFumyIix483B85sgiMjUp/AYPZ+O2 lNmvga4mdhMhvXcJisDRQi0SH2TF9WZ3QbmuIYY9Y2B0G2AzuU7qEe1NtNQaD5atovvo HRjVxAWWFbzotqQoAdJil1KpWKCi2hBhKtWU6dwbymqsX8dD60ntCWYkPar6IS7pSl05 Yo7X9xOrhbePd60UXlunfATLsbwXfiWkcslkjHyHr61MdKkoViBl79JIKyHxi9dC5yQ6 jFhodicHLy0YDL7HXA2afG0CpS1NA1F2NzM7XeuR54zCltwJl2V6qqZ2xcSYVHH0HJRx OfHQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=wm8GUc74DQde1SldX5v+QDGq6Ckjj0MF+TZnfV4oKTg=; b=gO9/+MIBpEsjwUrBrhCSJPxuGfd3hMq8eEhCf+AzgtCmQVBWqmPPpZw3UWJ1vcm22U on6cFM40cfY7Fo5KVeOW20rRcOv4x6/p5sMwSXjVazH0ZyCPATFfgyuaGn3Q2jj1kKsq AtP5H72G4rTmiTPN94CQMN5oyYzfVKOAhR+61BKR/RqjCTmRrT/r+W2omXHLEinqMU+S P1J3tGRqD+M/ixM/HUxgVXMkuMeSXkTUmEzYxZ7Lm5H5E1KxoPK2SH7GOrGXsmEnzb7a 6g9CZEzgmxtdOVKnZkc+Fqva2WgwQV+MQ5PNOg6qb/5IAS1Bzd6OrrfBdk1nSOailCd2 TCvQ== X-Gm-Message-State: AOAM532rY9CTzS04bt7GDe836jo21G3AcVuP7HbxWtP5eUGnKHwzxRFK /MryYBCd2O7FMc6Wx9EaZut2ptpPmQ6VM+jxLJKHZmF+yFk= X-Google-Smtp-Source: ABdhPJytll6dbitOLEBPJsKJWKE8WAra/HrrsYmHIv2I39KHINN4Bp0tYBLZT8tRHx9AHF71352meBCXzyF6pwynL1w= X-Received: by 2002:a9d:5a03:: with SMTP id v3mr5513608oth.17.1641959119356; Tue, 11 Jan 2022 19:45:19 -0800 (PST) MIME-Version: 1.0 References: <20211231234039.GU31637@mcvoy.com> <20220101005605.GL75481@eureka.lemis.com> <20220101031511.GB8135@mcvoy.com> <20220110203300.GY3441@mcvoy.com> <695e2970-00f2-ab55-8c1a-9fbd03add77f@mhorton.net> <69B0EA6A-3B99-4555-AD08-F67FAF52A818@iitbombay.org> In-Reply-To: <69B0EA6A-3B99-4555-AD08-F67FAF52A818@iitbombay.org> From: Dan Cross Date: Tue, 11 Jan 2022 22:44:43 -0500 Message-ID: To: Bakul Shah Content-Type: multipart/alternative; boundary="0000000000000b851205d55a6655" Subject: Re: [TUHS] TeX and groff (was: roff(7)) X-BeenThere: tuhs@minnie.tuhs.org X-Mailman-Version: 2.1.26 Precedence: list List-Id: The Unix Heritage Society mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: TUHS main list Errors-To: tuhs-bounces@minnie.tuhs.org Sender: "TUHS" --0000000000000b851205d55a6655 Content-Type: text/plain; charset="UTF-8" On Tue, Jan 11, 2022 at 9:11 PM Bakul Shah wrote: > Don Knuth talks at length about how TeX & MetaFont came about etc. in his Web of Stories interview in parts 50 through 70. In Part 56 he does say he looked at "the system developed at Bell Labs", presumably troff. Among the Bell Labs technical reports I read when I was younger, a trilogy by MD McIlroy on the challenges drawing ellipses stand out: https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.49.3440&rep=rep1&type=pdf These stuck in my mind and some relatively short time later, I read how the analogous problem was approached in TeX. The solution there was to treat the shape as if it were drawn using a pen with a diamond-shaped nib. From the MetaFont book: Similarly, some diagonal lines of slope~1 digitize to be twice as dark as others, when a truly circular pen is considered. But the diamond-shaped nib that \MF\ uses for a pencircle of diameter~1 does not have this defect; all straight lines of the same slope will digitize to lines of uniform darkness. Moreover, curved lines drawn with the diamond nib always yield one pixel per column when they move more-or-less horizontally (with slopes between $+1$ and $-1$), and they always yield one pixel per row when they move vertically. By contrast, the outlines of curves drawn with circular pens produce occasional ``blots.'' Circles and ellipses of all diameters can profitably be replaced by polygons whose sub-pixel corrections to the ideal shape will produce better digitizations; \MF\ does this in accordance with the interesting theory developed by John~D. ^{Hobby} in his Ph.D. dissertation (Stanford University, 1985). If I can be so bold as to offer an interpretation: Doug's approximations treat ellipses as mathematical objects and algorithmically determine what pixels are closest to points on the infinitesimally-thin curves, while Knuth's (or one his students') method acknowledges that the curve has a width defined by the nib; any "pixel" the nib touches becomes part of the figure. Perhaps I'm wrong on the details, but it hardly matters; my point is that there was clearly interesting work done in the area in both places. I find it impossible that neither Knuth nor Hobby were unaware of McIlroy's work and vice-versa; of course he would have known about and examined troff just as the Bell Labs folks knew about TeX. These were hot areas of practical research! This is also a good reminder that not only was Unix itself a subject of research, but it supported a lot of other research at Bell Labs and elsewhere. On this list, we tend to focus on the tool, but that tool was put to use building many more things as well. > [snip] > I must say I am a fan of TeX/LaTeX and not a fan of nroff/troff -- I don't like the troff look and I don't like the markup. I've always admired the look of troff. I wonder if, in retrospect, that is due to me mentally tying the presentation with so many formative documents that were strong early influences. Similarly, I love the look of Tex (even the CM fonts). They are of course different, but I find each beautiful in different ways. > The nice thing is we can choose whatever typesetting tools we want! This! - Dan C. --0000000000000b851205d55a6655 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
On Tue, Jan 11, 2022 at 9:11 PM Bakul Shah <bakul@iitbombay.org> wrote:
> Don = Knuth talks at length about how TeX & MetaFont came about etc. in his W= eb of Stories interview in parts 50 through 70. In Part 56 he does say he l= ooked at "the system developed at Bell Labs", presumably troff.
Among the Bell Labs technical reports I read when I was younger, a tr= ilogy by MD McIlroy on the challenges drawing ellipses stand out: https://citeseerx.ist.psu.edu/viewdoc/download?= doi=3D10.1.1.49.3440&rep=3Drep1&type=3Dpdf

These stuck i= n my mind and some relatively short time later, I read how the analogous pr= oblem was approached in TeX. The solution there was to treat the shape as i= f it were drawn using a pen with a diamond-shaped nib. From the MetaFont bo= ok:

= Similarly, some diagonal lines of slope~1 digitize to be twice as dark as o= thers, when a truly
circular pen is considered. But the diamond-shaped n= ib that \MF\ uses
for a pencircle of diameter~1 does not have this defec= t; all straight
lines of the same slope will digitize to lines of unifor= m darkness.
Moreover, curved lines drawn with the diamond nib always yie= ld one pixel per
column when they move more-or-less horizontally (with s= lopes between $+1$
and $-1$), and they always yield one pixel per row wh= en they move vertically.
By contrast, the outlines of curves drawn with = circular pens produce
occasional ``blots.'' Circles and ellipses= of all diameters can profitably
be replaced by polygons whose sub-pixel= corrections to the ideal shape
will produce better digitizations; \MF\ = does this in accordance with the
interesting theory developed by John~D.= ^{Hobby} in his Ph.D.
dissertation (Stanford University, 1985).
If I can be so bold as to offer an interpretation: Doug's appr= oximations treat ellipses as mathematical objects and algorithmically deter= mine what pixels are closest to points on the infinitesimally-thin=C2=A0cur= ves, while Knuth's (or one his students') method acknowledges that = the curve has a width defined by the nib; any "pixel" the nib tou= ches becomes part of the figure. Perhaps I'm wrong on the details, but = it hardly matters; my point is that there was clearly interesting work done= in the area in both places. I find it impossible that neither Knuth nor Ho= bby were unaware of McIlroy's work and vice-versa; of course he would h= ave known about and examined troff just as the Bell Labs folks knew=C2=A0ab= out TeX. These were hot areas of practical research! This is also a good re= minder that not only was Unix itself a subject of research, but it supporte= d a lot of other research at Bell Labs and elsewhere. On this list, we tend= to focus on the tool, but that tool was put to use building many more thin= gs as well.

> [snip]
> I must say I am a fan of TeX/LaTeX a= nd not a fan of nroff/troff -- I don't like the troff look and I don= 9;t like the markup.

I've always admired the look of= troff. I wonder if, in retrospect, that is due to me mentally tying the pr= esentation with so many formative documents that were strong early influenc= es. Similarly, I love the look of Tex (even the CM fonts). They are of cour= se different, but I find each beautiful in different ways.

> The nice thing is we can choose whatever typesetting tools we want!=

This!

=C2=A0 =C2=A0 =C2= =A0 =C2=A0 - Dan C.

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