$1\mathrm{.}1.$ Task $2$: Construct Polynomial$-$Order Terms

We assume $$not only includes the first$-$order terms of the input variables, but also includes the higher$-$order polynomial terms. Thus, we need to use the first order term $($system variables$)$to construct all the polynomial$-$order terms including and below order $5.$

We use the following command to construct all the terms under order $5$

poly$=$PolynomialFeatures$(5)$

PhiX$=$poly.fit$\_$transform$($X$)$