Easy-Fit Solution of complex identification problems with minimal implementation efforts
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Parameter equation differential equation differential

Easy-Fit Description

Easy-Fit is an interactive program that will identify parameters in different functions and equations. The software can handle explicit model functions, dynamical systems of equations, Laplace transformations, systems of ordinary differential equations, differential algebraic equations, or systems of one-dimensional time-dependent and algebraic 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 function may depend also on an additional independent variable that could represent for example a concentration value of an experiment. The system is capable to compute optimum designs. Main features: User interface: extensive database coming with 1.300 examples convenient modeling language with automatic differentiation alternative Fortran interface up to 30 fitting criteria and data sets syntax-highlighting editor extensive report and graphics facilities, also for Gnuplot in- and output of data by text files or Excel General: arbitrary fitting criteria depending on the parameters to be estimated, and the solution of the dynamic system additional nonlinear equality or inequality constraints second independent model variable called concentration switching points with restart of integration, e.g., for changing the model variable switching times, e.g., for modeling dynamical input functions alternative norms (sum of absolute values, maximum of absolute values) confidence intervals for estimated parameters, correlation and covariance matrix identification of significance levels for estimated parameters computation of optimal experimental designs (A-criterion) Ordinary differential equations (ODE): explicit and implicit solvers stiff and large ordinary differential equations, band structures shooting method for unstable ordinary differential equations Ordinary differential algebraic equations (DAEs): algebraic equations up to index 3 consistent index-1-initial values evaluated internally One-dimensional, time-dependent partial differential equations (PDEs): coupled ordinary differential equations different integration areas with non-continuous transitions large number of discretization procedures upwind formulae and ENO method for hyperbolic equations boundary conditions in Dirichlet or Neumann form or as implicit algebraic equations Database with 1.300 examples: 243 explicit model functions 41 steady state systems 10 Laplace transforms 575 ordinary differential equations 62 differential algebraic equations 325 one-dimensional, time-dependent partial differential equations 44 one-dimensional partial differential algebraic equations

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