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3.2 Subcircuit and Device Model Definition 205
InitialGuess
InitialGuess−>{var −>value , var −>value , † † † }
specify initial guesses for the values of behavioral model
variables
Format of the InitialGuess argument.
With the InitialGuess argument, you can specify a set of numerical values that will be used
by NDAESolve (Section 3.7.5) as initial guess for the solution of behavioral model variables. Initial
guesses may be specified for some or all of the variables listed in the corresponding Variables
declaration.
The default value for initial guesses is 0.
When you analyze strongly nonlinear circuits, an educated initial guess helps to speed up
DC calculations with NDAESolve considerably.
The effect of initial guess specifications on the convergence behavior of NDAESolve depends
on the type of circuit equations.
In the example shown below, initial guesses of V and V are specified for the model variables
vdeff and Voltage["A", "C"], respectively. No initial guess is given for Current["A", "C"],
therefore, NDAESolve uses 0 as initial guess for this current.
Model[
Name −> "Diode", Selector −> "DC",
Ports −> {"A", "C"}, Parameters −> {Rs, Is, Global[Vt]},
Variables −> {Voltage["A", "C"], Current["A", "C"], vdeff},
Definition −> Equations[
Voltage["A", "C"] − Rs*Current["A", "C"] − vdeff == 0,
Current["A", "C"] == Is*(Exp[vdeff/Vt] − 1)
],
InitialGuess −> {vdeff −> 0.7, Voltage["A", "C"] −> 0.8}
]
InitialConditions
InitialConditions−>{var −>value , var −>value , † † † }
specify initial conditions for dynamic model variables
Format of the InitialConditions argument.