Splitting of some s-domain stability-test algorithms

Some classic s-domain algorithms are first expressed in a unified form. From this, all possible split forms are then derived and classified. In particular, attention is focused on two families of algorithms, which include the standard Routh algorithm and an s-domain Levinson-like algorithm respectively. The related split forms are analysed and compared. Their complexity can be reduced by suitably choosing some scaling factors. It turns out that the usual form of the Routh algorithm, which is intrinsically split, and the simplified version of the split Levinson-like algorithm are substantially equivalent and superior to any other possible split algorithm.     

An extension to ‘an algorithm for rinding a circuit of even length in a directed graph’

Most of the empirical studies modelling the association between slock returns and accounting earnings assume a homogeneous return-earnings relation across firms and over time. However, in recent years some studies have reported that this association significantly varies across firms and also over time. Whether macro-economic factors explain the intertemporal variation of earnings response coefficients (ERCs), i.e. the slope coefficients between stock returns and corporate earnings in the Finnish stock market is studied. In the theoretical part of the study it is shown that there exists a relationship between macroeconomic variables affecting future cash flows/dividends or pricing operator and the intertemporal variation of earnings response coefficients. The empirical analysis reveals some time-series variation of ERCs in the Finnish stock market. A significant proportion of this variation is observed to be due to the changes in the underlying macroeconomic characteristics.     

Model reduction using the output equation error

A model-reduction method based on the minimization of the output equation error for suitable inputs is presented. The method is characterized by remarkable computational simplicity and flexibility compared with other reduction methods based on equation errors. The practicability of the proposed procedure is discussed and some examples are given.     

Symbolic expression of transfer functions in compartmental systems with control

A systematic method to derive the symbolic expression of an I/O transference of a general compartmental system is presented. Each step of the procedure is illustrated by a meaningful example. A proof based on the application of Mason's formula to the equivalent signal flow graph is also given