On Wed, 14 Jul 2010, Henrique Andrade wrote: > I have 2 time-series, X and Y, and I need to create a new one, Z, that is > defined as: > > Z(1) = X(1) > Z(2) = Z(1) + Y(2) > Z(3) = Z(2) + Y(3) > . > . > . > Z(n) = Z(n-1) + Y(n) > > Where Z(1) is the first observation of the series Z, Z(2) is the second > observation of the series Z, and so on. > > How can I do this with Gretl? series Z = X[1] Z = Z(-1) + Y No rocket science required.