The file `fontmath.cfg`

can contain declarations relating to the use
of fonts in math mode.

If it exists, it defines which fonts in which sizes are used in math mode, and how they are used. It also defines all the math mode commands that `are likely to' depend on the choice of math fonts used (e.g. commands that depend on the position of a glyph in a math font).

The main reason for the existence of this file is to provide for future
updates when a standard math font encoding is available. Right now we
do *not* encourage the use of this configuration file other than
for special applications. Writing a proper configuration file for math
mode needs expert knowledge!

Please note carefully the above **warning**.