\begin{Schunk}
\begin{Sinput}
 mymod <- lm(y~x)
 gqtest(mymod, fraction=0.2, order.by= ~ x)
\end{Sinput}
\begin{Soutput}
	Goldfeld-Quandt test

data:  mymod
GQ = 4.497, df1 = 198, df2 = 198, p-value < 2.2e-16
alternative hypothesis: variance increases from segment 1 to 2
\end{Soutput}
\end{Schunk}
