Inasmuch as AH Formatter supports MathML 3.0 but on Linux ships with a minimal `font-config.xml`

file, if you are formatting non-trivial MathML on Linux, then you’ll probably need to add some mathematical fonts to your `font-config.xml`

.

If counts as trivial because you could do it with “ordinary” fonts, then non-trivial would include anything requiring “stretchy” characters, such as the identity matrix example from the MathML 3.0 spec that is shown on the right rendered without and with mathematical fonts. AH Formatter on Linux uses the STIX fonts by default, so the simplest way to get your MathML rendering correctly is to make sure that the STIX fonts are installed and that AH Formatter will use them. Continue reading