Man pages matching name infnan in section 3:

infnan.3.es	debian 10 / manpages-es
infnan.3.ja	debian 10 / manpages-ja-dev
infnan.3.pt	debian 10 / manpages-pt-dev
infnan.3.ja	debian 11 / manpages-ja-dev
infnan.3.pt	debian 11 / manpages-pt-dev