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    How does one write in Tex for MathOverflow the symbols of the real numbers, and the complex numbers? Usually, one uses \mathds, but this doesn't seem to work.
    • CommentAuthorykallus
    • CommentTimeApr 6th 2013
    I didn't know about mathds (presumably for "double stroke"?). I always use mathbb (for "blackboard bold"), which I believe works here.

    I find it interesting what people think is "usual" with respect to TeX, and I am frequently surprised when I try to fix the TeX on MathOverflow questions that display poorly. As it happens, I've almost never seen mathds used.

    In addition to mathbb, many use mathbf (boldface). I've even heard purists claim that blackboard bold should be reserved for blackboards.

    If you want to emulate some of the old Springer lecture notes, you can superimpose two Cs or mush a C and an I together using negative spaces.

    • CommentAuthorXet
    • CommentTimeApr 6th 2013
    The shortest method might be \Bbb
    • CommentAuthorAngelo
    • CommentTimeApr 6th 2013
    Does anyone really miss the look of the old, typewritten Springer lecture notes?

    Perhaps "mathds" is available only if you first load a certain package into LaTeX. Since "mathbb" is available in Mathjax (used here by default), that is what I use here.

    • CommentAuthorEmil J
    • CommentTimeApr 8th 2013
    @Gerald Edgar: Indeed, \mathds comes from package dsfont.

    \Bbb is deprecated even in TeX. Please do not use it.


    @frederico poloni: \Bbb is not deprecated in Plain TeX or AMS TeX. In fact, in these packages \Bbb is the only way to access the font under discussion.

    Also, you seem to be confusing TeX (a program written by Knuth) and Plain TeX (a macro package for TeX, just like AMS TeX and LaTeX).


    @Dmitri Pavlov: I see your point; let me replace my statement with this one, which should be correct and informative: \Bbb is deprecated in LaTeX (where it is provided by the package amsfonts).

    I used that wording because, at least in my professional circle, "TeX" is used nowadays as a generic term to denote "TeX with one of its commonly used macro packages, typically LaTeX". I am aware that it is not accurate, but it's the common use. It's a bit like "sellotape", "xerox" or "Linux".