Management of a large block-diagonal macro-economic model in APL

Abstract

KESSU-model is a large medium-term input-output-based macroeconomic model. Its APL-based on-line design consists of model estimation, structural management of the model, model simulation and analysis of simulation results. The structural management is based on the concept of the list of model variables and the list of model blocks. In the compilation phase, model blocks are input as character matrices and transformed with processor functions to variable sublists and coefficient matrices, using the list of model variables as a control data. Variable sublists and reduced form coefficient matrices together with the variable list and list of model blocks are input to an iterative model solution procedure, which is performed with a FORTRAN compiled program for cost reasons. The model solution is coupled with the APL system by means of an interface designed to transfer the model structure and input data for simulation, and results back to APL workspace for further processing and reporting. There are some encouraging test results showing that a pure APL solution is competitive in cost terms, if satisfactory starting values for iteration are given.