webuse grunfeld,clear
reshape wide invest mvalue kstock,i(year) j(company)
forv i=1/4 {
	local eqns "`eqns' (invest`i' mvalue`i' kstock`i')"
	}
sureg `eqns'	
mat cns = J(6,13,0)
local nc 1
forv i=1/2 {
	forv j=0(3)6 {
		mat cns[`nc',`i'+`j'] = 1
		mat cns[`nc',`i'+`j'+3] = -1
		local ++nc
		} 
	}
mat list cns
mat_put_rr cns
test

mat makeCns cns
mat dispCns
sureg `eqns', c(1/6)