// y=b0*x*x + b1*x + b2
function SimpleParabola(const B: TVec; X: double): double;
begin
  SimpleParabola := b[0]*Sqr(x) + b[1]*x + b[2];
end;

double __fastcall SimpleParabola(TVec * const b, double x)
{
  double* B = b->PValues1D(0);
  return B[0]*x*x + B[1]*x + B[2];
}