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From: chris@umcp-cs.UUCP (Chris Torek)
Newsgroups: net.text
Subject: Re: DVI question
Message-ID: <1671@umcp-cs.UUCP>
Date: Thu, 6-Dec-84 21:32:21 EST
Article-I.D.: umcp-cs.1671
Posted: Thu Dec  6 21:32:21 1984
Date-Received: Sat, 8-Dec-84 07:05:01 EST
References: <256@zinfandel.UUCP>
Organization: U of Maryland, Computer Science Dept., College Park, MD
Lines: 22

> Can someone tell me if the .DVI files produced by DiTroff and
> the .DVI files produced by TeX are the same or different formats??

They are most emphatically *not* the same.  DiTroff's ``device
independent'' output is different for each device; I think it's
misnamed; it should be called ``device specific'' output.  (Don't
get me wrong: I think ditroff is quite an improvement over troff.)

TeX's output is precisely the same for every device; in fact, TeX
itself doesn't care *what* device will eventually be used.  The
basic approach to device independence is different.  Instead of
using the ultimate output resolution as internal units, TeX uses
``scaled points'' (sp), where 2**16 sp == 1 point == 1/72.27 in.
This comes out to 4,765,777.92 points per inch, which is enough
resolution that roundoff errors disappear.  (In fact, you'd have
to use a powerful microscope to detect a difference of a few sp.)
-- 
(This line accidently left nonblank.)

In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (301) 454-7690
UUCP:	{seismo,allegra,brl-bmd}!umcp-cs!chris
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