# Overview of DEQSOL

How to use DEQSOL to solve/fit differential equations

1. Select a chosen set of differential equations from a DLL or ASCII text model file and control DEQSOL interactively or from data files, configure/initialise, or parameter/limits files.
2. Select the integration method to use (i.e. BDF/Adams).
   Note that some special releases of DEQSOL offer a wider choice of integration methods.
3. Select tolerances/error-test/transformation as required.
4. Select a range of integration and the number of points.
   Note that integration will always be advanced from x = 0, irrespective of the range chosen for simulation, fitting, or plotting.
5. Select parameters p(i) and initial conditions y0(i).
   Note that the y0(i) will always be assumed to refer to y(i) values at x = 0.
6. Select a sub-set of y(i) components for special attention if there are a large number of equations.
   This is essential if there are more than twleve equations.
7. Plot/tabulate/file the specially selected y(i) solutions.
8. Compare the result with alternative solutions (e.g. steady state solutions or approximate integrals).
   Note that this procedure is only available in some special releases of DEQSOL.
9. Read in data then plot/overlay before curve-fitting.
10. You can use a configure/initialise file to set all the parameters, limits, methods, time range, etc. but this can be appended to user-supplied model files.
    Also parameter-limits files can be used to just set parameters and limits.
11. For details of how to supply differential equations as a DLL or ASCII text file, read the readme.? files, the manual and the test example files deqmod?.tf?.

Back to Help Menu or End Help