# In plain tex, how to use Small Caps in equations?

In LaTeX, we can write

$T_{\textsc{max}}$

In plain TeX, we can do thing like

\font\scshape=cmcsc10

{\scashape max}.

But this method does not work inside . We cannot write

$T_{{\scshape max}}$

So is there any way to make it work?

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$T_{\hbox{\scshape max}}$ should work … –  Qrrbrbirlbel Mar 30 '13 at 20:39
Perhaps $T_{\hbox{\scriptsize\scshape max}}}$ –  Aditya Mar 30 '13 at 20:41
@Qrrbrbirlbel that would make a textsize subscript though. –  David Carlisle Mar 30 '13 at 21:07
@Aditya \scriptsize isn't in plain. –  David Carlisle Mar 30 '13 at 21:08
@DavidCarlisle Yes, it was more of a pointer than a solution. Op didn’t define any other fonts to use … –  Qrrbrbirlbel Mar 30 '13 at 21:09

    \font\scshapex=cmcsc10
\font\scshapevii=cmcsc10 at 7pt
\font\scshapev=cmcsc10 at 5pt

\newfam\scfam
\textfont\scfam\scshapex
\scriptfont\scfam\scshapevii
\scriptscriptfont\scfam\scshapev

${\fam\scfam Max}(T) = T_{\fam\scfam Max}$

\bye

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Without defining a math family:

\font\tensc=cmcsc10
\font\sevensc=cmcsc10 at 7pt
\font\fivesc=cmcsc10 at 5pt

\def\mathsc#1{{\mathchoice
{\hbox{\tensc#1}}
{\hbox{\tensc#1}}
{\hbox{\sevensc#1}}
{\hbox{\fivesc#1}}
}}

$\mathsc{Max}(T) = T_\mathsc{Max}$

\bye


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