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2.7 Time-Domain Analysis of Nonlinear Dynamic Circuits 121
2.7.4 NDAESolve Options
Options[NDAESolve]
Several options are available for NDAESolve most of which need not be changed unless there are
problems with the default settings, such as convergence problems. To list all options associated with
NDAESolve inspect the value of Options[NDAESolve]:
In[23]:= Options[NDAESolve]
Out[23]=
AccuracyGoal 6, AnalysisMode Transient,
BreakOnError False, Compiled True, CompressEquations False,
DesignPoint Automatic, InitialConditions Automatic,
InitialGuess Automatic, InitialSolution Automatic,
InterpolationOrder 1, MaxDelta 1., MaxIterations 100, 20,
MaxSteps Automatic, MaxStepSize Automatic,
MinStepSize Automatic, NonlinearMethod FindRoot,
OutputVariables All, Protocol InheritedAnalogInsydes,
RandomFunction RandomReal, 0., 0.1 &,
ReturnDerivatives False, Simulator InheritedAnalogInsydes,
SimulatorExecutable Automatic, StartingStepSize Automatic,
StepSizeFactor 1.5, WorkingPrecision 16
Below, a set of NDAESolve options is explained in more detail:
InitialGuess
With the default setting InitialGuess −> Automatic, zero is used as initial guess for all variables
when solving a system of nonlinear equations by means of Newton iterations. Whenever this setting
causes numerical problems, such as division-by-zero errors or failure to converge, you can use
InitialGuess to specify your own initial guess as a list of rules of the form:
InitialGuess −> {var −> value , , var n −> value n }
Note that the variables var i are specified without the time variable tvar.
InitialSolution
With the option InitialSolution we can force NDAESolve to use a certain DC solution as initial
operating point for a transient analysis. A set of initial values must be provided as a list of rules
which associate a numerical value with a variable from the system of equations. Missing variables
are then computed consistently.
InitialSolution −> {var −> value , , var n −> value n }
Note that the variables var i are specified without the time variable tvar.
MaxDelta
One of the conditions that are checked by the integration step size control mechanism is whether the
values of some variables change abruptly from one time step to the next. The maximum allowed