Man pages matching name signbit in section 3:

signbit.3.en	debian 10 / manpages-dev
signbit.3.es	debian 10 / manpages-es
signbit.3.ja	debian 10 / manpages-ja-dev
signbit.3.en	debian 11 / manpages-dev
signbit.3.es	debian 11 / manpages-es-dev
signbit.3.fr	debian 11 / manpages-fr-dev
signbit.3.ja	debian 11 / manpages-ja-dev
signbit.3.en	debian 12 / manpages-dev
signbit.3.es	debian 12 / manpages-es-dev
signbit.3.fr	debian 12 / manpages-fr-dev
signbit.3.ja	debian 12 / manpages-ja-dev
signbit.3.ru	debian 12 / manpages-ru-dev