y = a1 + a2 x1 + a3 x12 + (a4 + a5 x1 + a6 x12) x2
function quadraticLinear extends Modelica.Icons.Function; input Real a[6] "Coefficients"; input Real x1 "Independent variable for quadratic part"; input Real x2 "Independent variable for linear part"; output Real y "Result"; end quadraticLinear;