Difference between revisions of "Math/stackers"
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− | $\mathover[symbol]{"2217}{A}$, % 2217 is | + | $\mathover[symbol]{"2217}{A}$, % 2217 is unicode for asterisk |
− | $\mathover[symbol]{"2218}{A}$, % 2218 is | + | $\mathover[symbol]{"2218}{A}$, % 2218 is unicode for circle |
− | $\mathover[symbol]{"2219}{A}$, % 2219 is | + | $\mathover[symbol]{"2219}{A}$, % 2219 is unicode for bullet |
$\mathunder[symbol]{"2217}{A}$, | $\mathunder[symbol]{"2217}{A}$, | ||
$\mathunder[symbol]{"2218}{A}$, | $\mathunder[symbol]{"2218}{A}$, |
Revision as of 11:05, 12 May 2024
Contents
\mathover, \mathunder and \definemathstackers
ConTeXt has a nice structure called mathstackers
in order to define new math commands in which some characters
are stacked over another one. For more information refer to math-stc.mkiv.
The two command \mathover[symbol]{}{
} and \mathunder[symbol]{}{
} are built and can be used directly.
\framed[frame=off]{% $\mathover[symbol]{"2217}{A}$, % 2217 is unicode for asterisk $\mathover[symbol]{"2218}{A}$, % 2218 is unicode for circle $\mathover[symbol]{"2219}{A}$, % 2219 is unicode for bullet $\mathunder[symbol]{"2217}{A}$, $\mathunder[symbol]{"2218}{A}$, $\mathunder[symbol]{"2219}{A}$.}
However one may define one's own commands.
A typical example is when you want to put a small circle on top of a letter (as one would when defining the topological interior of a set…).
To do so we define first a new stacker named here MySymbol
, and then invoking that with \definemathover
we define two new commands \interior
and \mystarred
which can be used in math mode.
\definemathstackers[MySymbol] [voffset=-.3\mathexheight, hoffset=\zeropoint, mathclass=ord, topoffset=.4\mathemwidth, % poor man's italic correction middlecommand=\mathematics] \definemathover[MySymbol][interior]["2218] %this a small circle \definemathover[MySymbol][mystarred]["2717] % this is an asterisk \starttext Here is the new command \type{\interior{K}}: $\interior{K}$. Compare this to \type{\mathring{K}}: $\mathring{K}$. Here is the new command \type{\mystarred{K}}: $\mystarred{K}$. Here are the built-in commands \type{\mathover} and \type{\mathunder}: $\mathover[symbol]{"2217}{A}$, % 2217 is an asterisk $\mathover[symbol]{"2218}{A}$, % 2218 is a circle $\mathover[symbol]{"2219}{A}$, % 2219 is a bullet $\mathunder[symbol]{"2217}{A}$, $\mathunder[symbol]{"2218}{A}$, $\mathunder[symbol]{"2219}{A}$. \stoptext
When typeset in mkiv
one can see that the command \interior{K
} shows the letter K with a small circle above it.
Overbraces and underbraces
In math mode, you can put a brace over or under an expression this way:
\startformula a + \overbrace{b + c} + \underbrace{d + e} + \doublebrace{f + g} + h \stopformula
The same goes for brackets (or other stackers):
\startformula a + \overbracket{b + c} + \underbracket{d + e} + \doublebracket{f + g} + h \stopformula
Adjusting stackers
You can adjust where the stackers start and end with the lt
(left-top), rt
(right-top), lb
(left-bottom) and rb
(right-bottom) parameters.
This feature was introduced in beta 2019-10-28.
$a + \overbrace [lt=1em] {b+c+d} + e$\blank $a + \underbrace [lt=1em] {b+c+d} + e$\blank $a + \overbrace [rb=1em] {b+c+d} + e$\blank $a + \underbrace [rb=1em] {b+c+d} + e$\blank $a + \overbrace [lt=1em,rb=1em] {b+c+d} + e$\blank $a + \underbrace [lt=1em,rb=1em] {b+c+d} + e$\blank
Interleaved braces
Some terms of an expressions can be shared by both braces, tuning the lt
, rt
, lb
and rb
parameters:
$a + \doublebrace[lt=1.4em,rt=-.3em] {b+c+d} + e$\blank $a + \doublebrace[rb=1em] {b+c+d} + e$\blank $a + \doublebrace[lt=1.4em,rt=-.3em,lb=-.3em,rb=1.5em] {b+c+d} + e$\blank $a + \doublebrace[lt=-1.6em,rb=-1.4em] {b+c+d} + e$\blank
See also
- Chapter "1. Math stackers" in the About manual.
- Section "1.8 Accents" in the Still manual.
- Section "10.6 Fancy fences" in the Math-MkIV manual.