Questions tagged [tex-core]
{tex-core} is for questions for syntax, semantics and expected behavior of TeX primitive control sequences, regardless of extensions (eTeX, etc.) formats (Plain or LaTeX) and macro packages (tikz). Such questions usually relate to low-level TeX programming or the behaviour of TeX at an underlying level. Note that even Plain TeX is a format in itself; for questions about it, use {plain-tex}.
1,962
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Why is "^^62" "v" and "^^6" "b" in TeX?
With TeX, ^^62^6\bye produces vb.
Hex 62 is 98 in Dec, bigger than 64, so 98-64=34. From cmr10 table, the 34th slot is ". Why is it v?
6 is smaller than 64, so 6+64=70. From cmr10 table, the ...
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votes
2
answers
233
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Show carriage return by changing its catcode in TeX?
On page 46 of The TeXbook, there is
TEX deletes any space characters (number 32) that occur at the right end of an input line. Then it inserts a return character (number 13) at the right end of the ...
- 1,715
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2
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104
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What follows the `^^` in TeX? Hex or Dec or symbol?
^^6\bye will produces v. I can understand this. 6 is the symbol of ASCII table, and the DEC of 6 symbol is 54. As 54 is smaller than 64, so 54+64=128. The 128th symbol of ASCII table is v.
^^61 ...
- 1,715
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1
answer
51
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Why can the character number 127 be ouput by default?
On page 44 of The TeXbook, it says,
the “dangerous bend” sign used in this manual appears as character number 127 of font manfnt, and that font is selected by the control sequence \manual
On page 45 ...
- 1,715
2
votes
3
answers
852
views
"^^A" does not work in TeX?
On page 45 of The TeXbook,
TEX has a standard way to refer to the invisible characters of ASCII: Code 0 can be typed as the sequence of three characters ^^@, code 1 can be typed ^^A, and so on up to ...
- 1,715
0
votes
3
answers
127
views
How to understand "\appendroman#1#2#3" on page 41 of The TeXbook?
At the bottom of page 41 of The TeXbook, there is a question:
Define a control sequence \appendroman with three parameters such that \appendroman#1#2#3 defines control sequence #1 to expand to a ...
- 1,715
6
votes
2
answers
1k
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Doesn't "\romannumeral1986" equal "mcmlxxxvi" in TeX?
In TeX,
\uppercase{\romannumeral1986}\par
%\catcode`\m=12
\uppercase{mcmlxxxvi}
\bye
produces
So, doesn't mcmlxxxvi equal \romannumeral1986? What the difference between them? \expandafter can bypass ...
- 1,715
4
votes
2
answers
477
views
"\uppercase{a\lowercase{bC}}" produces "Abc" in TeX?
In TeX, \uppercase{a\lowercase{bC}} produces Abc not ABC, why? As far as I know, TeX will run the inner group before run the outer group, so I think it should be ABC and even \uppercase{a\expandafter{\...
- 1,715
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1
answer
55
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"\escapechar" vs category 0 in TeX
In TeX, \catcode`\|=0 will make escape character to be |, to |TeX will output
But at the penultimate paragraph of page 40 of The TeXbook, it says that \escapechar is normally TeX's internal code for ...
- 1,715
1
vote
1
answer
108
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To make "\" to category 12, why should convert it to category 13 in TeX？
Exercise 7.5 on page 40 of The TeXbook asks to make \ to category 12. The answer of this question is
{\catcode‘/=0 \catcode‘\\=13 /message{/string\}}
Why should assign the \ to 13 not 12?
The ...
- 1,715
0
votes
1
answer
73
views
Doesn't "\csname" need contain "\0"?
On page 40 of The TeXbook,
Conversely, you can go from a list of character tokens to a control sequence by saying ‘\csname\endcsname’.
So \csname TeX\endcsname equals \TeX. However, \TeX contains ...
- 1,715
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39
views
Why does '\string' convert '\' to "? [duplicate]
On page 40 of the TeXbook, it says, \string\cs will produce tokens to be calssied to 12. But \string\TeX will produce `"TeX" as
I once thought that the result should be \TeX. Why is there &...
- 1,715
0
votes
2
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69
views
Need add a space before character in changing category of character?
At the bottom of page 307 of The TeXbook, it says
TEX always reads the token following a constant before evaluating that constant.
So,
{\catcode‘\>=2 >
is different from
{\catcode\`>=2>
...
- 1,715
2
votes
1
answer
118
views
What is the '\oops' in 'I\errorcontextlines=100 \oops' and where should they be placed in TeX file?
At the bottom of page 34 of The TeXbook, there is
If you use TEX format packages designed by others, your error messages may involve many inscrutable two-line levels of macro context. By setting \...
- 1,715
2
votes
1
answer
220
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Does '\centerline' really define '\ERROR' in TeX?
In a .tex file, there is \centerline{\bf A SHORT \error STORY}, which will cause error as
l.3 \centerline{\bf A SHORT \ERROR STORY}
?
! Emergency stop.
<...
- 1,715
3
votes
1
answer
246
views
"Underfull" or "Loose" box in TeX?
When badness exceeds \hbadness, there should be Underfull. When badness exceeds \tolerance, there should be Overfull. Origin story.tex file is
\hrule
\vskip 1in
\centerline{\bf A SHORT STORY}
\vskip ...
- 1,715
4
votes
1
answer
105
views
Same badness cause different space in the same sentence in TeX?
On page 29 of The TeXbook, Mr. Knuth show the same sentence with the same badness, but those have different space between their word. What is the reason and how to understand the badness here?
- 1,715
3
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2
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405
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Is "plain.fmt" equal "plain.tex" in TeX?
When tex was input in terminal, there is preloaded format=tex. Is preloaded format=tex equal plain.tex? When input &plain \input story after the tex command, there is
Sorry, I can't find the ...
- 1,715
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votes
3
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80
views
numbers greater or equal condition
can't believe that there is a language in which such a simple thing requires so much effort.
well i want to do a greater or equal to comparison of an argument in a macro. My current try is not right.
...
- 952
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2
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53
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If one of TEX’s internal parameters is changed within a group, the previous contents of that parameter will be restored when the group ends in TeX?
I see this sentence on page 21 of the book The TeXbook, but I can't understand it. May you show me an example and explain it to me?
If one of TEX’s internal parameters is changed within a group, the ...
- 1,715
0
votes
2
answers
66
views
Without "\global", we can still change "\count0"?
As on page 21 of the book The TeXbook, if we need to change the page number to add 1, we need to use \global\advance\count0 by 1, as \advance\count0 by 1 couldn't change \count0 in other groups. ...
- 1,715
2
votes
1
answer
110
views
"\kern0pt" could correct the "\/" before comma or period in TeX?
For easier use of {\it text}, we can define a control sequence such as \def\ital#1{{\it #1\/}}, which is suggested at the bottom of page 20 of the TeXbook. Since it will add extra space, which is not ...
- 1,715
5
votes
1
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452
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"\tenrm" is not built into TEX. but why can it be used directly?
On page 15 of the book The TEXbook : a complete user's guide to computer typesetting with TEX, Mr. KNUTH said that
Each font used in a TEX manuscript is associated with a control sequence; for ...
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4
votes
1
answer
156
views
String-separated arguments in LaTeX
One of the features I like best in Plain TeX is the ability to write macros with arguments separated by a sensible delimiter. For example
\def\translate#1 = #2 (#3){...}
What is the LaTeX way of ...
- 309
3
votes
2
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457
views
Get upright italic fonts in TeX
I can get italic fonts in TeX by \it command, but I see there is upright italic font on page 13 of the book The TeXbook. How did the author achieve this style?
See the words
while the letters in ...
- 1,715
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1
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150
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Why there are 256 different control sequences of length 2 and 256^2 of length 3 in TeX?
On page 11 of the book The TeXbook, there is a question:
How many different control sequences of length 2 (including the escape character) are possible? How many of length 3?
The answer is:
There ...
- 1,715
3
votes
1
answer
140
views
"\null?" doesn't add a space after the question mark
On the page 34 of the book TEX for the Impatient, there is:
TEX normally adds some extra space after what it thinks is a punctuation mark at the end of a sentence, namely, ‘.’, ‘?’, or ‘!’ followed ...
- 1,715
6
votes
4
answers
1k
views
How does \if work?
In the definition of \if on page 209 in TeXbook it is said:
unless the current equivalent of that control sequence has been \let
equal to a non-active character token
Do I understand it correctly ...
- 7,043
-2
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3
answers
278
views
How does TeXbook macro \stest work?
Let's put the \stest macro from TeXbook to file stest.tex with some
formatting and adding line numbers for reference.
1 \newif\ifspace \newif\iffunny \newif\ifexplicit \newif\ifactive
2 \def\stest#...
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3
votes
1
answer
244
views
Why space is [not] ignored in macro arguments?
Test 1 prints SPACE IGNORED. From this we conclude that space from \s is ignored while argument scanning.
Test 2 differs from test 1, that * is appended to parameter list.
If space is ignored while ...
- 7,043
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1
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47
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how to toogle tex boolean inside lualatex code
I have classical tex boolean:
\newif\ifprintanswers
\printanswersfalse
I also have luacode that can read some environment variable:
\begin{luacode}
if os.getenv('C') == '1' then
tex....
- 45
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0
answers
22
views
Opmac Footnotes with no newline
I'm using OPMAC footnote macros in Plain TeX.
I am trying to format multiple footnotes on one page so they are next to each and not positioned on a new line. At the moment it formats like
But I need ...
- 59
0
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0
answers
74
views
Code positioning [duplicate]
Does Latex allow the true and false statements to be placed on the same line ?
\IfNoValueTF {#5} { \hspace{0.5cm} } { \ (#5) \par\smallskip }
rather than
\IfNoValueTF {#5}
{ \hspace{0.5cm} }
{ ...
user305917
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0
answers
31
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Is there a package offering a command inserting a or an depending on whether a fovel follows? [duplicate]
The question is already the headline:
is there a package which provides a command say \a
which expands to an if a spoken vowel follows, else to a?
Maybe this is a bit too specific,
because it refers ...
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2
votes
1
answer
316
views
new LuaTeX primitives documentation
Compared to pdfeTeX, which primitives have been added to LuaTeX?
Besides the rearrangement of the standard pdfeTeX PDF primitives, and the somewhat odd (as compared to XeTeX) beaviour of \font (which ...
- 4,257
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1
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608
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Failed to install MikTeX
Today, I tried to install the current MikTeX version (basic-miktex-23.10-x64.exe, published on 10/06/2023), which was downloaded from the MikTeX homepage. Unfortunately, I get the following bizarre ...
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1
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116
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Why does a \catcode-changed underscore work in math mode also without \mathcode set to "8000?
Something is puzzling me... consider
%\begingroup
%\catcode`\_=13
%\gdef_{\sb}
%\endgroup
\catcode`\_=11
\def\foo_bar{Foo bar}
\foo_bar\ $a_b$
\bye
Uncommenting the commented code yields
(One can ...
- 29.8k
9
votes
7
answers
562
views
Detect catcode of next character?
I use only lualatex, but I suspect this is a general question, having something to do with core TeX.
Is there such a thing as \ifnextcatcode ? Pseudo-code:
\def\wanted{\ifnextcatcode{12}{\dothis}{\...
- 1,327
-2
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1
answer
83
views
Descriptions for n, N, V, T, F [closed]
Where can I find descriptions for n, N, V, T, F. What are they called ? Generally found after commands.
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2
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150
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TeX program conceivable at all which produces output other than .dvi or .pdf directly, e.g., .rtf/.doc/.docx
Donald E. Knuth's TeX outputs .dvi files.
Hàn Thế Thành's pdfTeX outputs .pdf files.
Is a program rtfTeX or docTeX or docxTeX conceivable that instead of .dvi or .pdf directly outputs Word .rtf or ....
- 349
0
votes
1
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34
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pdflatex error due to empty *.pfb file in VSCode with LaTex Workshop
I'm working with jupyter notebooks in vscodeto export *.ipynb files to *.pdf. This works very well, but I'm not happy with the generated output. So I decided to make a *.tex file, to format it to my ...
- 101
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2
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191
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Pandoc PDF method for two-column layout in bibliography list section
I am seeking a method to format a document in two columns, including both the body and the bibliography reference list at the end.
My current workflow uses markdown columns within the body correctly, ...
- 23
3
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0
answers
64
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Are there tricks for detecting whether a `\csname..\endcsname`-thingie went wrong and, if so, delivering additional messages explaining the issue?
For the sake of having expandable tokens expanded before stringification I sometimes combine \csname..\endcsname-expansion with \string as in
\chardef\stopromannumeral=`\^^00
\edef\gobbleToPrefix{%
\...
- 27.5k
3
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1
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226
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Where is the definition of the math mod environment `$$...$$`?
I have a problem with display math modes $$...$$ and \[...\], see The display math mode and the `center` environment. So, I want to find the definition of the display math mode $$...$$ for ...
- 51
3
votes
1
answer
291
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TeX capacity exceeded, sorry [grouping levels=255]
I have a tikz graph of 484 nodes, about twice as many edges. As the error suggests, I am hitting some limit, but I am not sure which.
A graph of about 250 nodes renders fine. To add to my confusion, I ...
- 237
4
votes
1
answer
178
views
How to get the width of the gap actually produced in the output-file due to \hskip?
How to get the width of the gap actually produced in the output-file due to \hskip?
I wonder if there is a way in Knuthian TeX of getting the width of the gap actually produced in the output-file due ...
- 349
4
votes
3
answers
412
views
How does TeX distinguish between variables and procedures?
Every computer program evaluating anything has to distinguish between variables and procedures. This is a typical example from SICP:
(define (eval exp env)
(cond ((self-evaluating? exp) exp)
...
- 699
0
votes
1
answer
70
views
Exercise 5.7 in TeX - define control sequences with grouping
I want to solve Exercise 5.7 in the TeXBook by Donald E. Knuth.
Define control sequences **\beginthe**<block name> and **\endthe**<block name>
that provide a “named” block structure.
In ...
- 1
0
votes
3
answers
128
views
How do \left | and \right | actually work?
How do \left | and \right | actually work, specifically when packages like fontspec or mathspec are involved and unicode fonts are used?
I sort of understand how other kinds of brackets and ...
- 159
5
votes
2
answers
504
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Exercise 8.6 of The TeXbook
Exercise 8.6. Assume that the category codes of plain TEX are in force, except that the characters ^^A, ^^B, ^^C, ^^M belong respectively to categories 0, 7, 10, and 11. What tokens are produced from ...
- 513