I am typesetting a long mathematical text (lecture notes), in which I use the alphabets

\mathbb A
\mathcal A
\mathfrak A

very often, so I decided to name them

\A \sA \fA

(For bb A, script A, fraktur A resp.). Now I want to shorten my preamble by creating a helper

    \newcommand{\#1}{\mathbb #1}
    \newcommand{\s#1}{\mathcal #1}
    \newcommand{\f#1}{\mathfrak #1}

which doesn't work since the \#1 etc. seem to not be expanded.
How can I wirte a macro which defines those three commands given a single letter as input?

Thanks for any help.

  • It is strange. Why not define 3 new commands? If your code works what would you type: \mathletter{A}?
    – Sigur
    Commented Jan 27, 2014 at 14:23
  • Because that means 26*3 = 78 lines of code vs. 36+5 = 41 lines, about half and much more readable than a bunch of \newcommand{\X}{\mathbb X} lines
    – AlexR
    Commented Jan 27, 2014 at 14:26
  • 2
    This might be what you're looking for: tex.stackexchange.com/questions/28704/…
    – Snicksie
    Commented Jan 27, 2014 at 14:30
  • 1
    Does this suffice: \documentclass{article} \usepackage{amssymb} \def\B#1{\mathbb #1} \def\C#1{\mathcal #1} \def\F#1{\mathfrak #1} \begin{document} $\B A \C A \F A $ \end{document} Commented Jan 27, 2014 at 14:34
  • 1
    @AlexR, you don't need to retype. You can use Find/Replace tools.
    – Sigur
    Commented Jan 27, 2014 at 14:37

1 Answer 1


Thanks to @Snicksie, I have been able to come up with the following:

Note that this is not really "beautiful" and that it overwrites the commands \H,\L,\O,\P,\S but I have confirmed that I need none of them and "manually" undefined them so I get errors when I oversee any other commands.

    \expandafter\newcommand\csname #1\endcsname{\mathbb #1}
    \expandafter\newcommand\csname s#1\endcsname{\mathcal #1}
    \expandafter\newcommand\csname f#1\endcsname{\mathfrak #1}
\mathletter A
\mathletter B
\mathletter C
\mathletter Z

Another very elegant solution, thanks to @StevenB.Segelets is to define:

\def\B#1{\mathbb #1}
\def\C#1{\mathcal #1}
\def\F#1{\mathfrak #1}

And use those slighly different commands then. This doesn't redefine any existing macros and therefor is probably a cleaner solution, but requires to change previous syntax (\A, \sA, \fA) in all documents and thus requires some "rewriting".

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