Am 22.09.2011 21:25, schrieb Joseph Wright:
>> In TeX the display counts as 3 lines (regardless of the number of real
>> lines it would occupy in a grid system).
> We should document that as part of the galley: I didn't know that :-)
>>> \clubpenalty => \clubpenalties is easy to understand, as both are
>>> related to the start of a paragraph.
>> not quite \clubpenalties refer to the beginning of every partial
>> paragraph. However \clubpenalty only refers to the penalty after the
>> first line of a paragraph.
> The interesting thing is that this is not the case. While I can't find
> it in The TeXbook or TeX by Topic, using \tracingall shows that, as the
> e-TeX manual says, \clubpenalty applies to each _partial_ paragraph. For
> example, try
looks like a typical lie from the TeX book (as Don said somewhere in the
book he does that sometimes). I just checked the code, it is indeed
apply at each start of a partial paragraph, but widowpenalty is applied
only to the very end; in front of a display \displaywidowpenalty is used
> So e-TeX\d generalisation is correct, its more that it's somewhat
> different to the one I expected :-)
yes looks like it.
>> Point is when I want to have at least 3 lines after a heading I should set
>> \interlinepenalties = 3 10000 10000 1000
>> <first para>
>> \interlinepenalties = 0
>> now if that para contains a display I still get only 3 lines fixed to
>> the heading.
of course my example above is wrong first of all I missed out one 0 but
more importantly the last value is repeated so you have to write instead
\interlinepenalties = 4 10000 10000 10000 0
if you want to achieve what I claimed
> What it seems is needed is an interface that makes sense, i.e. which
> separates out:
> 1) The general interline penalty
> 2) The penalty for lines(s) at the start of the paragraph as a whole
> 3) The penalty for lines(s) at the end of the paragraph as a whole
> 4) The penalty for line(s) before display math
> 5) The penalty for line(s) after display math
> 6) Additional penalties between arbitrary lines
> or some such structure. This will require a bit of thought, as it means
> synchronising the various primitives in an ordered way.
> One additional note from my experiments is that \interlinepenalties is
> reset by \par, in the same way \parshape is. I can't see this mentioned
> anywhere. In contrast, neither \interlinepenalty nor \clubpenalties are!
> Quite surprising.
looks like an oversight in the e-TeX manual. But it does make a lot of
sense to do this (actually very nice because that means you don't have
to bother about resetting).
As i said the main use case was preventing pagebreaks for a while
(couple of lines) after something like a heading, so essentially a
onetime operation, while culb and widow penaltis are intended for the
general visual behavior of (i like always at least 1 or tw lines of a
paragraph on a page if possible) so that this is typically a setting
that you want to generally apply.
however that is inconsistent with \interlinepenalty which stays the way
it is forever.