Man pages matching name qwtweedingcurvefitter in section 3:

QwtWeedingCurveFitter.3.en	debian 10 / libqwt-doc
QwtWeedingCurveFitter.3.en	debian 11 / libqwt-doc
QwtWeedingCurveFitter.3.en	debian 12 / libqwt-doc