Tī sò͘-ha̍k tiong, be̍k-hâm-sò͘ (冪函數; power function) sī chi̍t chióng hêng-sek chhin-chhiūⁿ f ( x ) = x r {\displaystyle f(x)=x^{r}} ê hâm-sò͘; kî-tiong, chí-sò͘ r {\displaystyle r} ē-ēng sī chū-jiân-sò͘ kap iú-lí-sò͘, iā thang sī jīm-hô si̍t-sò͘ ia̍h-sī ho̍k-cha̍p-sò͘.