# User talk:Peter Schmitt

## Welcome

Welcome to an experienced editor of Citizendium! --Boris Tsirelson 08:14, 8 January 2012 (CET)

Thank you, Boris! It was your CZ edit that made me look. There are so few users here, that I was not sure if this is already meant for the "public". But I thought that creating an account would not hurt. Peter Schmitt 11:52, 8 January 2012 (CET)
There are more than 100 registered users, but only two are active. About 20 were spammers. I guess, no one knows what exactly is meant here, but the future depends on us. Look here and you will know what happens; write there and your opinion will be voiced. --Boris Tsirelson 15:52, 8 January 2012 (CET)

Welcome also from my side. Yes, we still have few users, but you are right that we are not completely ready for the public. Hopefully this will be changed soon. Any help, especially from experienced wikipedians, is very welcome. --Ulf Rehmann 19:47, 9 January 2012 (CET)

Thank you. I hope I'll find the energy to contribute usefully ...
By the way, I'm glad you deleted "History of mathematics". Trivial stubs without any information are out of place here.
Peter Schmitt 16:10, 18 January 2012 (CET)
Yes, but it would be less brutal to also formulate a reason, at least. The author is not a bad guy. On Wikipedia, making a stub is considered useful. In fact, I still wonder, what kind of users are welcome here. It is not stated. Technically, everyone can get an account. If only professors are welcome, it should be said prominently. Or also graduate students? Where is the borderline? --Boris Tsirelson 16:56, 18 January 2012 (CET)
I considered leaving a note on his talk page (before the page was deleted) but I did not do it because I did not know what the policy is. --Peter Schmitt 21:07, 18 January 2012 (CET)
And I do not know either. And new users do not know. This is the problem. --Boris Tsirelson 22:32, 18 January 2012 (CET)
I have written to him by now. When I deleted that page, I got the impression from the 'delete' dialog that there was given a default hint to our editorial policy, which wasn't true. Sorry things are still a bit vague here (everything is in statu nascendi), but please keep nagging me if you find things inconvenient. Concerning accounts, there is no restriction.--Ulf Rehmann 00:29, 19 January 2012 (CET)

## Predefined macros

I just saw your test page. You may want to exercise MathJax interactively on this page. By the way, on EoM, \N --> $\N$ is predefined by some macros, among several others: $\Z \Q \R \C \dots$ (For some reason these predefinitions don't work on the above interactive link.) --Ulf Rehmann 12:10, 18 January 2012 (CET)

Ah, really! I was surprised to see the predefined $\R$. Can we have the complete list of predefined macros? (Sorry for abusing Peter's talk page.) --Boris Tsirelson 13:39, 18 January 2012 (CET)
This is not an abuse, Boris ;-) A list of predefined macros is indeed essential, or one is left to guessing ...
As for testing: Preview can also be used ... and it works with predefined macros. --Peter Schmitt 16:14, 18 January 2012 (CET)
Here is a list of predefined macros. I don't know to what extent it is complete, but at least those work. The list depends on the installation of mathjax as a wikimedia expansion.--Ulf Rehmann 00:16, 19 January 2012 (CET)
I discovered a potential problem: Two consecutive braces are interpretated as template in math mode, too.
$\def\a{{A}} \a$
This can be prevented by additional spaces. Usually (in math mode) this space will not hurt, but perhaps not always ...
Surprisingly, \bgroup and \egroup are not defined.
--Peter Schmitt 16:55, 18 January 2012 (CET)
Yes, the parsing of {{ ... }} is probably flawed. But it seems you can use {{{ ... }}} instead. -- Why would you want to have \bgroup and \egroup? According to Knuth, these are defined via '\let': '\let\bgroup={' and '\let\egroup=}'. And '\let' is not defined here either.--Ulf Rehmann 00:16, 19 January 2012 (CET)
Well, \bgroup and \hgroup are standard controlsequences both in plain TeX and in LaTeX. Thus it was natural to assume that they can be used. They are sometimes convenient instead of braces in order to make the code easier to read -- braces { and parentheses ( are often difficult to distinguish on a screen. But, more important, they are essential if you have to put an incomplete group into the replacement text of a macro, e.g., in order to open or close a \box or a token register \toks: It may be inconvenient -- and sometimes impossible -- to have the complete content as a macro. --Peter Schmitt 01:24, 19 January 2012 (CET)

## test

Can definitions be transcluded? $$\def\N{\mathbb N} % comment \def\Q{ {\bf Q}} % redefinition? \def\Sum.#1.#2 {\sum_{#1}^{#2}} % delimited parameters?$$ Test $\N$ MathJax

$\Q \Z \Sum.i=1.100 a_i$

$a = {c\over b}$

Obviously: Yes. That makes it possible to define a common set of macros for a group of related articles. --Peter Schmitt 01:32, 19 January 2012 (CET)

Fontsize: AA$A$A$\cal A$A

How to Cite This Entry:
Peter Schmitt. Encyclopedia of Mathematics. URL: http://encyclopediaofmath.org/index.php?title=Peter_Schmitt&oldid=21622