[Tex/LaTex] What’s the difference between \tolerance and \badness

line-breakingtex-core

I'm having some difficulty understanding this sentence on page 29, Chapter 6 of Knuth's TeXbook:

Run TeX again, and begin this time by
saying

\hsize=2in \tolerance=1600 \input story

so that lines with badness up to 1600
will be tolerated. Hurray! There are
no overfull boxes this time. (But you
do get a message about an underfull
box, since TeX reports all boxes whose
badness exceeds a certain threshold
called \hbadness; plain TeX sets
\hbadness=1000.)

Best Answer

The \tolerance setting influences the paragraph breaking routine itself: changes to \tolerance (and \pretolerance) actually affects which line breaks are chosen. Higher values allow worse lines (usually meaning: with stretched inter-word spaces) to be accepted, with the value 10000 indicating a 'panic mode' where anything at all is acceptable. Normally the lower the value, the better the paragraph will look, but you run the risk of reducing the list of possible breaks so much that you end up with overfull lines.

The \hbadness setting only influences the user report (the messages you see on screen and in the log) about the actually chosen lines, it has no effect on the breaking routine itself.

Related Solutions

[Tex/LaTex] New lines and TeX: difference between ^^J and ^^M

I think that what constitutes the end of line upon reading from a file is hardcoded according to whatever operating system you are running on. And that end of line is represented by the character whose number is \endlinechar.
When writing, the character whose number is \newlinechar will trigger the end of a line. Again, the exact result in the output file is hard coded, depending on your operating system.
See #1.
Usually, the argument to \scantokens is treated as a single line. Thus a percent sign in the argument to \scantokens will end input from this argument. However, any occurrences of the character whose number is \newlinechar will be used to split the argument into several lines.

To bring all these ideas together, consider the plain TeX file

\newlinechar=2
{\catcode`\%=12
 \gdef\foo{\scantokens{abc%xyz^^Bdef}}}%
\endlinechar=`X
\foo%
\bye%

which will typeset the text “abcdefX” .

(Edited to take into account what I learned about #4 from the comments.)

[Tex/LaTex] the difference between \newline and \\

From a usage point-of-view, there is a difference between \\ and \newline:

\\

Tells LaTeX to start a new line. This command has a starred version and takes an optional parameter:
- \\*: Similar to \\ but also tells LaTeX not to start a new page after the line by issuing a \nobreak.
- \\[<len>]: This specifies the vertical space <len> to be inserted before the next line. Can also be negative.
The above two can also be mixed. That is, using both a starred + optional argument combination \\*[<len>].
\newline

Similar to \\.

From a technical point of view (in latex.ltx), these commands are defined as follows, justifying the similarity between \\ (unstarred and without optional argument) and \newline:

\DeclareRobustCommand\\{%
  \let \reserved@e \relax
  \let \reserved@f \relax
  \@ifstar{\let \reserved@e \vadjust \let \reserved@f \nobreak \@xnewline}%
  \@xnewline}
\expandafter\let\expandafter\@normalcr
  \csname\expandafter\@gobble\string\\ \endcsname
\DeclareRobustCommand\newline{\@normalcr\relax}

LaTeX also redefines \\ to mean other things depending on the environment(s) you use. For example, within an array or tabular environment, the commonly-used \\ has a slightly different meaning to when it is used in regular text.

Best Answer

Related Solutions

[Tex/LaTex] New lines and TeX: difference between ^^J and ^^M

[Tex/LaTex] the difference between \newline and \\

Related Question