`\DeclareMathSizes`

`{`<*t-size*>`}` `{`<*mt-size*>`}` `{`<*s-size*>`}`
`{`<*ss-size*>`}`

Declares that <*mt-size*> is the (main) math text size, <*s-size*> is
the `script' size and <*ss-size*> the `scriptscript' size to be used
in math, when <*t-size*> is the current text size. For text sizes for
which no such declaration is given the `script' and `scriptscript'
size will be calculated and then fonts are loaded for the calculated
sizes or the best approximation (this may result in a warning
message).
Normally, <*t-size*> and <*mt-size*> will be identical; however, if,
for example, PostScript text fonts are mixed with bit-map math fonts
then you may not have available a <*mt-size*> for every <*t-size*>.
Example:

\DeclareMathSizes{13.82}{14.4}{10}{7}