: creates a column vector by stacking columns of x
<A HREF = "vech.m         ">vech           </A>: creates a column vector by stacking columns of x
<A HREF = "vecr.m         ">vecr           </A>: creates a column vector by stacking rows of x
<A HREF = "vprob.m        ">vprob          </A>: returns val = (1/sqrt(2*pi*he))*exp(-0.5*ev*ev/he)
<A HREF = "xdiagonal.m    ">xdiagonal      </A>: spreads an nxk observation matrix x out on
<A HREF = "yvector.m      ">yvector        </A>: repeats an nx1 vector y n t