USING ASCII TEXT FILES IN POST-FIX NOTATION (REVERSE POLISH) TO DEFINE MATHEMATICAL-MODELS AND SYSTEMS OF DIFFERENTIAL-EQUATIONS FOR SIMULATION AND NONLINEAR-REGRESSION

We discuss current methods for supplying equations in ASCII text form to executables for simulation or fitting, then we define a technique u sing stack notation that has many advantages over traditional approach es to this problem. Simulations are described to compare the cpu time consumed for function evaluation when the models are supplied as objec t code in dynamic-link libraries, and when they are supplied as ASCII text files in post-fix notation, otherwise known as last-in-first-out or reverse Polish. It is concluded that this new method is extremely c onvenient; it can be easily extended to include loops for numerical in tegration, special function evaluation or root finding; it can be opti mized by the user for execution speed; and the cpu overhead when the m odels are involved in regression are minimal. Copyright (C) 1996 Elsev ier Science Ltd