## Parameter Estimation in Dynamical Systems with EASY-FIT,
User's Guide, Version 2.0

K. Schittkowski: Report, Department of Mathematics, University of Bayreuth (1997)

**Abstract:**
EASY-FIT is an interactive software system to identify parameters in explicit model
functions, dynamical systems of equations, Laplace transformations, systems
of ordinary differential equations, differential algebraic equations and
systems of partial differential equations.
Proceeding from given experimental data, i.e. observation times and
measurements, the minimum least squares distance of measured data from a
fitting criterion is computed, that depends on the solution
of the dynamical system.
The model functions may depend also on an additional independent variable
that could represent for example a concentration value of an experiment.

The software system is implemented in form of a relational database
under MS-Access running under MS-Windows.
The underlying numerical algorithms are coded in FORTRAN and are executable
independently from the interface.
Model functions are either interpreted and evaluated symbolically by a
program called PCOMP, that allows in addition automatic differentiation of
nonlinear model functions, or by user-provided FORTRAN subroutines.
In the latter case interfaces for the Fortran compilers Watcom F77/386,
Salford FTN77, Lahey F77L-EM/32 and Microsoft Fortran PowerStation
are provided.