Man pages matching name qwtplotrescaler in section 3:

QwtPlotRescaler.3.en	debian 10 / libqwt-doc
QwtPlotRescaler.3.en	debian 10 / libqwt5-doc
QwtPlotRescaler.3.en	debian 11 / libqwt-doc
QwtPlotRescaler.3.en	debian 12 / libqwt-doc