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| − | This short article (being far from complete) is about Math and arrows used for vectors, as in <context>$\overrightarrow{AB}$</context>.
| + | moved to [[Math/Vectors]] |
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| − | If anyone feels like writing a more extensive article about math arrows in general, you're wellcome to do so.
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| − | == Vectors with arrows ==
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| − | === \vec, <context>$\vec{\strut}$</context> ===
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| − | The siplest way to write vectors is to use <code>\vec</code>:
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| − | <context source="yes">
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| − | $(\vec{\imath}, \vec{\jmath}, \vec{k})$
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| − | </context>
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| − | However, that solution is not applicable when one needs to use longer arrows, as in:
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| − | <context source="yes">
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| − | $\vec{AB}$
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| − | </context>
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| − | === \overrightarrow, <context>$\overrightarrow{\strut}$</context> ===
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| − | For such cases, the plain format provides another command, \overrightarrow:
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| − | <context source="yes">
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| − | $\overrightarrow{AB}$
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| − | </context>
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| − | Hovever, again, that command seems to be unsuitable for short letters:
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| − | <context source="yes">
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| − | $(\overrightarrow{\imath}, \overrightarrow{\jmath}, \overrightarrow{k})$
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| − | </context>
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| − | which means that one would need to combine both commands at best.
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| − | Another nasty property of \overrightarrow is that it doesn't scale down (textstyle, scriptstyle, ...):
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| − | <context source="yes">
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| − | $(X_{Y_{AB}}, X_{Y_{\overrightarrow{AB}}})$
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| − | </context>
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| − | ''Wait a minute ... has it really been fixed in ConTeXt when compared to plain TeX ???
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| − | That's not fair! I cannot demonstrate the problem now! ''
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| − | -- [[User:Mojca Miklavec|Mojca]] (crying)
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| − | Anyway, here's how it looks like in plain TeX:
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| − | <context>
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| − | $(X_{Y_{AB}}, X_{Y_{\displaystyle{\overrightarrow{AB}}}})$
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| − | </context>
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| − | == Vectors with harpoons ==
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| − | In some countries vectors are written with harpoons as opposed to arrows. Plain TeX has no support for that, add to that the fact that fonts have no suitable glyphs.
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| − | {{todo|clean the code (some might be in the core already), describe Aditya's macros}}
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| − | <context>
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| − | \unprotect
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| − | \def\mtharrowfill#1#2#3#4#5#6#7#8% AM: Added #8 (for displaystyle)
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| − | {$\mathsurround 0pt
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| − | \thickmuskip0mu\medmuskip\thickmuskip\thinmuskip\thickmuskip
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| − | \relax#8#5%
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| − | \mkern-#1mu
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| − | \cleaders\hbox{$#8\mkern -#2mu#6\mkern -#3mu$}\hfill
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| − | \mkern-#4mu#7$}
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| − | %D Now we need to make sure that the extensible arrows do not get
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| − | %D %D affected. So...
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| − | \def\domthxarr#1#2#3#4#5% hm, looks like we do a double mathrel
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| − | {\begingroup
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| − | \def\mtharrfactor{1}%
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| − | \def\mtharrextra {0}%
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| − | \processaction[#1] % will be sped up
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| − | [ \v!none=>\def\mtharrfactor{0},
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| − | \v!small=>\def\mtharrextra{10},
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| − | \v!medium=>\def\mtharrextra{15},
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| − | \v!big=>\def\mtharrextra{20},
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| − | \v!normal=>,
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| − | \v!default=>,
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| − | \v!unknown=>\doifnumberelse{#1}{\def\mtharrextra{#1}}\donothing]%
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| − | \mathsurround\zeropoint
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| − | \muskip0=\thirdoffourarguments #2mu
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| − | \muskip2=\fourthoffourarguments #2mu
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| − | \muskip4=\firstoffourarguments #2mu
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| − | \muskip6=\secondoffourarguments #2mu
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| − | \muskip0=\mtharrfactor\muskip0 \advance\muskip0 \mtharrextra mu
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| − | \muskip2=\mtharrfactor\muskip2 \advance\muskip2 \mtharrextra mu
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| − | \setbox0\hbox{$\scriptstyle
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| − | \mkern\muskip4\relax
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| − | \mkern\muskip0\relax
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| − | #5\relax
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| − | \mkern\muskip2\relax
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| − | \mkern\muskip6\relax
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| − | $}%
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| − | \setbox4\hbox{#3\displaystyle}% AM: Added displaystyle
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| − | \dimen0\wd0
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| − | \ifdim\wd4>\dimen0 \dimen0\wd4 \fi
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| − | \setbox2\hbox{$\scriptstyle
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| − | \mkern\muskip4\relax
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| − | \mkern\muskip0\relax
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| − | #4\relax
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| − | \mkern\muskip2\relax
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| − | \mkern\muskip6\relax
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| − | $}%
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| − | \ifdim\wd2>\dimen0 \dimen0\wd2 \fi
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| − | \setbox4\hbox to \dimen0{#3\displaystyle}% AM: added dislaystyle
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| − | \mathrel{\mathop{\hbox to
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| − | \dimen0{\hss\copy4\hss}}\limits^{\box0}_{\box2}}
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| − | \endgroup}
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| − | \let\domthxarrsingle\domthxarr
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| − | %D Now, for defining overarrows.
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| − | \def\definemathoverarrow
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| − | {\dotripleargument\dodefinemathoverarrow}
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| − | \def\dodefinemathoverarrow[#1][#2][#3]%
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| − | {\ifthirdargument
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| − | \setvalue{#1}{\dohandlemathoverarrow[#2][#3]}%
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| − | \else
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| − | \setvalue{#1}{\dohandlemathoverarrow[\zeropoint][#2]}%
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| − | \fi}
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| − | \def\dohandlemathoverarrow[#1][#2]%
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| − | {\mathpalette{\dodohanglemathoverarrow{#1}{#2}}}
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| − | % Note: math-pln has \kern-\onepoint, amsmath does not. I keep the
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| − | % % kern amount as an option. This is useful with overharpoons.
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| − | \def\dodohanglemathoverarrow#1#2#3#4%
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| − | {\vbox{\ialign{##\crcr
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| − | #2#3\crcr
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| − | \noalign{\kern#1\nointerlineskip}
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| − | $\m@th\hfil#3#4\hfil$\crcr}}}
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| − | \protect
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| − | \definemathoverarrow [overleftarrow] [\leftarrowfill]
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| − | \definemathoverarrow [overrightarrow] [\rightarrowfill]
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| − | \definemathoverarrow [overleftrightarrow] [\leftrightarrowfill]
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| − | %$\overleftarrow{A}$ $\overleftarrow{ABC}$
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| − | %$a_{\overleftarrow{A}}$ $b_{\overleftarrow{ABC}}$
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| − | %
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| − | %$\overleftrightarrow{A}$ $\overleftrightarrow{ABC}$
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| − | %
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| − | %$a_{\overleftrightarrow{A}}$ $b_{\overleftrightarrow{ABC}}$
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| − | \definemathoverarrow [overtwoheadrightarrow] [\twoheadrightarrowfill]
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| − | \definemathoverarrow [overtwoheadleftarrow] [\twoheadleftarrowfill]
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| − | \definemathoverarrow [overrightharpoondown] [1pt] [\rightharpoondownfill]
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| − | \definemathoverarrow [overrightharpoonup] [\rightharpoonupfill]
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| − | \definemathoverarrow [overleftharpoondown] [1pt] [\leftharpoondownfill]
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| − | \definemathoverarrow [overleftharpoonup] [\leftharpoonupfill]
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| − | \def\definemathshortarrow
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| − | {\dotripleargument\dodefinemathshortarrow}
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| − | \def\dodefinemathshortarrow[#1][#2][#3]%
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| − | {\ifthirdargument
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| − | \setvalue{#1}{\dohandlemathshortarrow[#2][#3]}%
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| − | \else
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| − | \setvalue{#1}{\dohandlemathshortarrow[\zeropoint][#2]}%
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| − | \fi}
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| − | \def\dohandlemathshortarrow[#1][#2]%
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| − | {\mathpalette{\dodohandlemathshortarrow{#1}{#2}}}
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| − | \def\dodohandlemathshortarrow#1#2#3#4%
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| − | {\setbox0\hbox{$\m@th#3#4$}%
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| − | \vbox{\ialign{##\crcr
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| − | \mirror{\clip[width=\wd0]{\mirror{$\m@th#2#3$}}}\crcr
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| − | \noalign{\kern#1\nointerlineskip}%
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| − | $\m@th\hfil#3#4\hfil$\crcr}}}
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| − | \definemathshortarrow [shortoverrightharpoonup]
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| − | [\rightharpoonup]
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| − | \let\myvec\shortoverrightharpoonup
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| − | $(\myvec{\imath},\myvec{\jmath},\myvec{k})$ or $\myvec{\nabla}$, $\myvec{\sigma}$, $\myvec{r}$ or $\displaystyle{A^{\myvec{ABCD}}}$
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| − | </context>
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| − | === \overrightharpoonup, <context>$\rightharpoonup$</context> ===
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| − | {{todo|compare sizes of different arrows}}
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| − | == Antykwa Toruńska ==
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| − | {{todo|Jacko and Janusz have added some extra glyphs - explore, describe the problem & solution and draw}}
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| − | \mathchardef\minusleft="32C9
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| − | \mathchardef\minusright="32CA
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| − | \mathchardef\minusc="32C8
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| − | == See also ==
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| − | This is a [[My Way]] about a related topic:
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| − | * [http://dl.contextgarden.net/myway/matharrows.pdf Extensible Arrows in ConTeXt] by Aditya Mahajan
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| − | [[Category:Math]]
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