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