How to make fonts bigger in **plain tex** math mode?

[Steve Litt]

Thanks Philip,

When I ran your code under luatex, here's what happened:

===============================================
[slitt at mydesk plaintex]$ luatex philip.tex 
This is LuaTeX, Version 1.16.0 (TeX Live 2023) 
 restricted system commands enabled.
(./philip.tex
! Font \sevenrm=cmr7  scaled 1440 not loadable: metric data not found
or bad. <to be read again> 
\relax 
l.12 \font\sevenrm=cmr7  scaled \magstep 2
                                         
? 
===============================================

So I know it's handling \magstep 2 correctly because it translates to
1440, but somehow it has trouble finding the metric data (for cmr7, I
guess). If I comment out that line, it does the same thing for the
cmr10 line. It errors out similarly with pdftex, tex, and luatex.

Thanks,

SteveT


Philip Taylor (Hellenic Institute) said on Fri, 28 Apr 2023 09:17:13
+0100

>On 28/04/2023 07:47, Steve Litt wrote:
>> How do I make fonts bigger in **plain tex** math mode?  
>
>Re-define the fonts and font families used in maths mode —
>
>$\forall x \in X, \quad \exists y \leq \epsilon$
>$$\forall x \in X, \quad \exists y \leq \epsilon$$
>
>\font\tenrm=cmr10 scaled \magstep 2
>\font\sevenrm=cmr7  scaled \magstep 2
>\font\fiverm=cmr5 scaled \magstep 2
>\font\teni=cmmi10  scaled \magstep 2
>\font\seveni=cmmi7  scaled \magstep 2
>\font\fivei=cmmi5 scaled \magstep 2
>\font\tensy=cmsy10 scaled \magstep 2
>\font\sevensy=cmsy7 scaled \magstep 2
>\font\fivesy=cmsy5 scaled \magstep 2
>\font\tenex=cmex10 scaled \magstep 2
>\font\tenbf=cmbx10  scaled \magstep 2
>\font\sevenbf=cmbx7 scaled \magstep 2
>\font\fivebf=cmbx5 scaled \magstep 2
>\font\tensl=cmsl10  scaled \magstep 2
>\font\tentt=cmtt10  scaled \magstep 2
>\font\tenit=cmti10  scaled \magstep 2
>
>\textfont1=\teni \scriptfont1=\seveni \scriptscriptfont1=\fivei
>\textfont2=\tensy \scriptfont2=\sevensy \scriptscriptfont2=\fivesy
>\textfont3=\tenex \scriptfont3=\tenex \scriptscriptfont3=\tenex
>
>$\forall x \in X, \quad \exists y \leq \epsilon$
>$$\forall x \in X, \quad \exists y \leq \epsilon$$
>
>\end
>
>-- 
>/Philip Taylor/
>


SteveT

Steve Litt 
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