The version for MediaWiki 1.31+ has some changes since previous versions:

By default the math rendering service from the Wikimedia Foundation located at
https://wikimedia.org/api/rest_v1/
will be used for math rendering.
Therefore php-curl is required.
cf. https://www.mediawiki.org/wiki/Manual:CURL

Consult https://www.mediawiki.org/wiki/Extension:Math for further information and advanced settings.

Attributes of the <math /> element:
attribute "display":
possible values: "inline", "block" or "inline-displaystyle" (default)

"display" reproduces the old texvc behavior:
The equation is rendered with large height operands (texvc used $$ $tex $$ to render)
but the equation printed to the current line of the output and not centered in a new line.
In Wikipedia users use :<math>$tex</math> to move the math element closer to the center.

"inline" renders the equation in with small height operands by adding {\textstyle $tex } to the
users input ($tex). The equation is displayed in the current text line.

"inline-displaystyle" renders the equation in with large height operands centered in a new line by adding
{\displaystyle $tex } to the user input ($tex).

For testing your installation run
composer phpunit:entrypoint -- extensions/Math/tests/phpunit/
from your MediaWiki home path.

== Logging ==
The math extension supports PSR-3 logging:
Configuration can be dona via
$wgDebugLogGroups['Math'] = [ 'level' => 'info', 'destination' => '/path/to/file.log' ];