<HTML><BODY STYLE="font:10pt verdana; border:none;"><DIV><FONT size=2> <P>Hi,</P> <P>I need help regarding estimating a linear model where restrictions are imposed on the coefficients. An example is as follows:</P> <P>Y_{t+2}=a1Y_{t+1} + a2 Y_t + b x_t + e_t</P> <P>restriction</P> <P>a1+ a2 =1</P> <P>Is there a function or a package that can estimate the coefficient of a model like this? I want to estimate the coefficients rather than test them.</P> <P>Thank you for your help</P> <P>Ahmad Abu Hammour </P></FONT></DIV></BODY></HTML>