Math formulas are not working on ptwikibooks. For an example, see
https://pt.wikibooks.org/wiki/Project:Caixa_de_areia?oldid=257996&action=edit&preview=yes&uselang=en
where it is displayed the following error:
Falhou ao verificar gramática (O executável texvc não foi encontrado. Consulte math/README para instruções da configuração.): K = \frac{1}{2} mv^2
The text comes from [[MediaWiki:math_failure]] and [[MediaWiki:Math_notexvc]], which in English are the following:
Failed to parse (Missing texvc executable; please see math/README to configure.)
Currently, we are using MediaWiki 1.22wmf6 (b16555d).
Version: wmf-deployment
Severity: major
See Also:
https://bugzilla.wikimedia.org/show_bug.cgi?id=48991