Problems with mfplain

Question

When I read the file mfplain into Metapost, I get about a dozen error messages complaining about redundant and inconsistent equations. It's hard to believe that there is really anything wrong with mfplain. Any idea what might be going wrong ?

The details of the interaction are as follows:

C:\Program Files (x86)\MikTex\miktex\bin>mpost
This is MetaPost, version 1.504 (MiKTeX 2.9)
**\relax
(mpost.mp (C:/Program Files (x86)/MikTex/metapost/base/plain.mp
Preloading the plain mem file, version 1.004))
*\input mfplain
(C:/Program Files (x86)/MikTex/metapost/base/mfplain.mp
Preloading the plain base, version 0.99: preliminaries,
basic constants and mathematical macros,
macros for converting units,
! Inconsistent equation (off by 2.77794).
<to be read again>
                   ;
l.230 mm*bpppix_=2.83464;
                               pt*bpppix_=0.99626;
?
[[ followed by a dozen or so similar messages ]]

Answer 1

mfplain.mp is designed to do very different things than plain.mp; if you want to build a Metafont as a Type3 font with Metapost, then something like

mpost -mem=mfplain cmr10.mf

will do.

Since version 1.5 (if I remember correctly), mpost doesn't really load .mem files any more, but it loads plain.mp by default. To get mfplain.mp in interactive mode, you can also call mpost -ini:

egreg% mpost -ini
This is MetaPost, version 1.504 (kpathsea version 6.1.0)
**mfplain
(/usr/local/texlive/2012/texmf-dist/metapost/base/mfplain.mp
Preloading the plain base, version 0.99: preliminaries,
 basic constants and mathematical macros,
 macros for converting units,
 macros and tables for various modes of operation,
 macros for drawing and filling,
 macros for proof labels and rules,
 macros for character and font administration,
and a few last-minute items.)
*