Hello,
This is just for discussion. I used to think that in doing mathematical 
calculations, the matrices need not to be mixed up with series. For the 
sake of clarityone can not, let's say multiply a series by a matrix. Is 
that right?
Well, in the following script this kind of multiplication works fine. Is 
that normal -- I mean, an intentionnally built feature -- or should we 
avoid such a mixed operation?
nulldata 100
series x1 = normal()
matrix unit = ones($nobs,1)
scalar prod = unit'*x1      # matrix * series
matrix mx1 = x1
scalar prod = unit'*mx1     # matrix * matrix
best,
artur