Mdthbs

Can an SPI slave start a transmission in full-duplex mode?

Did WWII Japanese soldiers engage in cannibalism of their enemies?

Does a code snippet compile? Or does it gets compiled?

Do other countries guarantee freedoms that the United States does not have?

Why should public servants be apolitical?

In the movie Harry Potter and the Order or the Phoenix, why didn't Mr. Filch succeed to open the Room of Requirement if it's what he needed?

Can I call myself an assistant professor without a PhD

Why couldn't soldiers sight their own weapons without officers' orders?

Shabbat clothing on shabbat chazon

What is the best way to cause swarm intelligence to be destroyed?

Is TA-ing worth the opportunity cost?

I want to copy my HOME folder to a USB flash drive but I can't. I accidentally removed Python 3 and lost many important stuff

Can a College of Swords bard use Blade Flourishes multiple times in a turn?

During the Space Shuttle Columbia Disaster of 2003, Why Did The Flight Director Say, "Lock the doors."?

What is a "Genuine Geraldo interviewee"?

Yajilin minicubes: the Hullabaloo, the Brouhaha, the Bangarang

Colleagues speaking another language and it impacts work

Could one become a successful researcher by writing some really good papers while being outside academia?

How do we avoid CI-driven development...?

How does The Fools Guild make its money?

English - Acceptable use of parentheses in an author's name

Why does this Pokémon I just hatched need to be healed?

Blocking people from taking pictures of me with smartphone

Looking for a new job because of relocation - is it okay to tell the real reason?

Does LaTeX redefine [some] TeX primitives?

What is the difference between TeX and LaTeX?How is char processed in math mode?Why is there no mudimendef primitive?What is the difference between empty and @empty?Why isn't everything expandable?Creating new primitivesInput/Output primitives of TeXKnuth “Some Implementations of TeX”…Commands in TeX which are different in LaTeXHow to make commands defined by def behave as strings?Should different TeX implementations (e.g. MiKTeX's and TeX Live's) produce identical DVI files?Different file opened by openin (was: between 2017 and 2018)

.everyoneloves__top-leaderboard:empty,.everyoneloves__mid-leaderboard:empty,.everyoneloves__bot-mid-leaderboard:empty{ margin-bottom:0;
}

6

I read in "What is the difference between TeX and LaTeX?" that LaTeX is a collection of macros (an extension) built on top of TeX. Supposedly, TeX primitives should then behave in LaTeX the same way they do in TeX. However, it seems it is not always the case. In "How is char processed in math mode?", it is explained why char behaves in text mode differently from math mode. But this is only in TeX. In LaTeX, however, char behaves identically in text and math modes, as it can be seen from the following example:

documentclass{article}  

  begin{document}

    In text mode, we obtain char"5. In math mode, we also obtain $char"5$.

  end{document}

In TeX, the result is different:

In text mode, we obtain char"5. In math mode, we obtain $char"5$.

bye

It seems that some TeX primitives (at least one: char) are redefined in LaTeX. I would like to know whether TeX primitives must be redefined in LaTeX. If yes, why? Are there other TeX primitives that are redefined in LaTeX? Are not TeX and LaTeX expected to produce the same result on such a simple piece of code (as in the example)?

tex-core

share|improve this question

edited 6 hours ago

siracusa

7,82122 gold badges1818 silver badges3535 bronze badges

asked 8 hours ago

spyglass007spyglass007

3333 bronze badges

New contributor

spyglass007 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

add a comment | 

6

I read in "What is the difference between TeX and LaTeX?" that LaTeX is a collection of macros (an extension) built on top of TeX. Supposedly, TeX primitives should then behave in LaTeX the same way they do in TeX. However, it seems it is not always the case. In "How is char processed in math mode?", it is explained why char behaves in text mode differently from math mode. But this is only in TeX. In LaTeX, however, char behaves identically in text and math modes, as it can be seen from the following example:

documentclass{article}  

  begin{document}

    In text mode, we obtain char"5. In math mode, we also obtain $char"5$.

  end{document}

In TeX, the result is different:

In text mode, we obtain char"5. In math mode, we obtain $char"5$.

bye

It seems that some TeX primitives (at least one: char) are redefined in LaTeX. I would like to know whether TeX primitives must be redefined in LaTeX. If yes, why? Are there other TeX primitives that are redefined in LaTeX? Are not TeX and LaTeX expected to produce the same result on such a simple piece of code (as in the example)?

tex-core

share|improve this question

edited 6 hours ago

siracusa

7,82122 gold badges1818 silver badges3535 bronze badges

asked 8 hours ago

spyglass007spyglass007

3333 bronze badges

New contributor

spyglass007 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

add a comment | 

I read in "What is the difference between TeX and LaTeX?" that LaTeX is a collection of macros (an extension) built on top of TeX. Supposedly, TeX primitives should then behave in LaTeX the same way they do in TeX. However, it seems it is not always the case. In "How is char processed in math mode?", it is explained why char behaves in text mode differently from math mode. But this is only in TeX. In LaTeX, however, char behaves identically in text and math modes, as it can be seen from the following example:

documentclass{article}  

  begin{document}

    In text mode, we obtain char"5. In math mode, we also obtain $char"5$.

  end{document}

In TeX, the result is different:

In text mode, we obtain char"5. In math mode, we obtain $char"5$.

bye

It seems that some TeX primitives (at least one: char) are redefined in LaTeX. I would like to know whether TeX primitives must be redefined in LaTeX. If yes, why? Are there other TeX primitives that are redefined in LaTeX? Are not TeX and LaTeX expected to produce the same result on such a simple piece of code (as in the example)?

tex-core

share|improve this question

edited 6 hours ago

siracusa

7,82122 gold badges1818 silver badges3535 bronze badges

asked 8 hours ago

spyglass007spyglass007

3333 bronze badges

New contributor

spyglass007 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

documentclass{article}  

  begin{document}

    In text mode, we obtain char"5. In math mode, we also obtain $char"5$.

  end{document}

In text mode, we obtain char"5. In math mode, we obtain $char"5$.

bye

share|improve this question

edited 6 hours ago

siracusa

7,82122 gold badges1818 silver badges3535 bronze badges

asked 8 hours ago

spyglass007spyglass007

3333 bronze badges

New contributor

spyglass007 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

share|improve this question

edited 6 hours ago

siracusa

7,82122 gold badges1818 silver badges3535 bronze badges

asked 8 hours ago

spyglass007spyglass007

3333 bronze badges

New contributor

spyglass007 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

edited 6 hours ago

siracusa

7,82122 gold badges1818 silver badges3535 bronze badges

edited 6 hours ago

siracusa

7,82122 gold badges1818 silver badges3535 bronze badges

asked 8 hours ago

spyglass007spyglass007

3333 bronze badges

New contributor

spyglass007 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

asked 8 hours ago

spyglass007spyglass007

3333 bronze badges

1 Answer
1

active

oldest

votes

4

LaTeX redefines the primitives input, end, -, /, underline and, in some contexts, par. It does not redefine char, but it uses different math codes.

In plain TeX we see

mathcode`^^E="023A % lnot

but LaTeX doesn't assign a mathcode to ^^E (ASCII 5), so the value is as initially, that is, 5.

When TeX processes char<number> in math mode, it uses the mathcode of the character, just as if the character was directly input. So in plain TeX you get character "3A in family 2 (lnot); in LaTeX you get character "5 in family 0.

Redefined primitives

• 
  input is redefined to allow input{<filename>};


• 
  end is redefined to mark the end of environments;


• 
  - and / are redefined for technical reasons;


• 
  underline is redefined to be also used in text mode.

As far as par is concerned, the redefinitions are essential for list-like environments.

Why does plain TeX assign a math code to ASCII 5?

Because Knuth used extended character sets and his keyboard allowed to directly input ¬ and other characters. So he found it convenient to set math codes for the extended character set.

share|improve this answer

edited 7 hours ago

answered 8 hours ago

egregegreg

761k9090 gold badges19871987 silver badges33373337 bronze badges

add a comment | 

Your Answer

StackExchange.ready(function() {
var channelOptions = {
tags: "".split(" "),
id: "85"
};
initTagRenderer("".split(" "), "".split(" "), channelOptions);

StackExchange.using("externalEditor", function() {
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled) {
StackExchange.using("snippets", function() {
createEditor();
});
}
else {
createEditor();
}
});

function createEditor() {
StackExchange.prepareEditor({
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: false,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: null,
bindNavPrevention: true,
postfix: "",
imageUploader: {
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
},
onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
});


}
});

spyglass007 is a new contributor. Be nice, and check out our Code of Conduct.

draft saved

draft discarded

Sign up or log in

StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});

Sign up using Google

Sign up using Facebook

Sign up using Email and Password

Post as a guest

Name

Email

Required, but never shown

StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2ftex.stackexchange.com%2fquestions%2f503599%2fdoes-latex-redefine-some-tex-primitives%23new-answer', 'question_page');
}
);

Post as a guest

Name

Email

Required, but never shown

4

LaTeX redefines the primitives input, end, -, /, underline and, in some contexts, par. It does not redefine char, but it uses different math codes.

In plain TeX we see

mathcode`^^E="023A % lnot

but LaTeX doesn't assign a mathcode to ^^E (ASCII 5), so the value is as initially, that is, 5.

When TeX processes char<number> in math mode, it uses the mathcode of the character, just as if the character was directly input. So in plain TeX you get character "3A in family 2 (lnot); in LaTeX you get character "5 in family 0.

Redefined primitives

• 
  input is redefined to allow input{<filename>};


• 
  end is redefined to mark the end of environments;


• 
  - and / are redefined for technical reasons;


• 
  underline is redefined to be also used in text mode.

As far as par is concerned, the redefinitions are essential for list-like environments.

Why does plain TeX assign a math code to ASCII 5?

Because Knuth used extended character sets and his keyboard allowed to directly input ¬ and other characters. So he found it convenient to set math codes for the extended character set.

share|improve this answer

edited 7 hours ago

answered 8 hours ago

egregegreg

761k9090 gold badges19871987 silver badges33373337 bronze badges

add a comment | 

4

LaTeX redefines the primitives input, end, -, /, underline and, in some contexts, par. It does not redefine char, but it uses different math codes.

In plain TeX we see

mathcode`^^E="023A % lnot

but LaTeX doesn't assign a mathcode to ^^E (ASCII 5), so the value is as initially, that is, 5.

When TeX processes char<number> in math mode, it uses the mathcode of the character, just as if the character was directly input. So in plain TeX you get character "3A in family 2 (lnot); in LaTeX you get character "5 in family 0.

Redefined primitives

• 
  input is redefined to allow input{<filename>};


• 
  end is redefined to mark the end of environments;


• 
  - and / are redefined for technical reasons;


• 
  underline is redefined to be also used in text mode.

As far as par is concerned, the redefinitions are essential for list-like environments.

Why does plain TeX assign a math code to ASCII 5?

Because Knuth used extended character sets and his keyboard allowed to directly input ¬ and other characters. So he found it convenient to set math codes for the extended character set.

share|improve this answer

edited 7 hours ago

answered 8 hours ago

egregegreg

761k9090 gold badges19871987 silver badges33373337 bronze badges

add a comment | 

LaTeX redefines the primitives input, end, -, /, underline and, in some contexts, par. It does not redefine char, but it uses different math codes.

In plain TeX we see

mathcode`^^E="023A % lnot

but LaTeX doesn't assign a mathcode to ^^E (ASCII 5), so the value is as initially, that is, 5.

When TeX processes char<number> in math mode, it uses the mathcode of the character, just as if the character was directly input. So in plain TeX you get character "3A in family 2 (lnot); in LaTeX you get character "5 in family 0.

Redefined primitives

• 
  input is redefined to allow input{<filename>};


• 
  end is redefined to mark the end of environments;


• 
  - and / are redefined for technical reasons;


• 
  underline is redefined to be also used in text mode.

As far as par is concerned, the redefinitions are essential for list-like environments.

Why does plain TeX assign a math code to ASCII 5?

Because Knuth used extended character sets and his keyboard allowed to directly input ¬ and other characters. So he found it convenient to set math codes for the extended character set.

share|improve this answer

edited 7 hours ago

answered 8 hours ago

egregegreg

761k9090 gold badges19871987 silver badges33373337 bronze badges

mathcode`^^E="023A % lnot

share|improve this answer

edited 7 hours ago

answered 8 hours ago

egregegreg

761k9090 gold badges19871987 silver badges33373337 bronze badges

answered 8 hours ago

egregegreg

761k9090 gold badges19871987 silver badges33373337 bronze badges

answered 8 hours ago

egregegreg

761k9090 gold badges19871987 silver badges33373337 bronze badges