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From: eijkhout@s41.csrd.uiuc.edu (Victor Eijkhout)
Newsgroups: comp.text.tex
Subject: Re: TeX bug or feature?
Message-ID: <1991May15.223441.23055@csrd.uiuc.edu>
Date: 15 May 91 22:34:41 GMT
References: <13021@uhccux.uhcc.Hawaii.Edu>
Sender: news@csrd.uiuc.edu (news)
Organization: UIUC Center for Supercomputing Research and Development
Lines: 56

julian@uhunix2.uhcc.Hawaii.Edu (Julian Cowley) writes:

>Can anyone explain to me why TeX sets \pagegoal to the g present
>at the end of the page breaking algorithm rather than the g for
>the best break?

The \pagegoal is set to the \vsize when the first
nondiscardable item is added to the current page.
After that it doesn't change, except when an insertion occurs:
rather than adding insertions to the \pagetotal
they are subtracted from the \pagegoal, which makes
sense, because the text of the page has to fit in
\vsize so why not decrease that?

>  Here's an example:

>%% goal height=1288.40509, max depth=4.0
>% t=22.0 g=1288.40509 b=10000 p=100 c=100000#
>% t=34.0 g=1288.40509 b=10000 p=0 c=100000#
            ^^^^
>    .
>    .
>    .
>% t=1042.0 plus 17.0 minus 12.0 g=1063.1112 b=190 p=150 c=440#
                                   ^^^^
You must have had an insertion between these two lines.

>% t=1054.0 plus 17.0 minus 12.0 g=1063.1112 b=15 p=0 c=115#
>% t=1066.0 plus 17.0 minus 12.0 g=1063.1112 b=1 p=100 c=201
                                   ^^^^
>% split254 to -16.83324,12.0 p=-10000
                         ^^^^
>% t=1078.0 plus 17.0 minus 12.0 g=1051.1112 b=* p=0 c=*
                                   ^^^^

And this looks like a split insertion, leaving 12pt (that is,
one line) to be placed on the current page. Beats me
how you can force to split to a negative value, but
hey, they're your macros.

Anyhow, the \pagegoal is again diminished by 12pt.

>I would have expected \pagegoal to equal 1063.1112, and I can

If anything you would have had to have expected 1288.40509,
is what I think...

>This really messes
>up an output routine I'm working on!

Yes, I know the feeling.

>Julian Cowley / U. of Hawaii at Manoa	| "God is love." -- John, c. 60 A. D.
>julian@uhunix.uhcc.hawaii.edu		| "All you need is love." -- John, 1967

Victor Eijkhout.