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2.7 Time-Domain Analysis of Nonlinear Dynamic Circuits 123
Protocol
With the option setting Protocol −> Notebook, NDAESolve can be instructed to print protocol
information to your notebook as the computation proceeds. The protocol includes an output of the
initial guess, the initial transient solution, shows the percentage of the computation completed, and
the number of time steps which were necessary to carry out the computation. The default setting is
Protocol −> Inherited[AnalogInsydes] which means that NDAESolve inherits the option setting
from the global setting specified in Options[AnalogInsydes]. See also Section 3.14.5.
StartingStepSize
The option StartingStepSize helps to overcome convergence problems at the beginning of a
simulation. If NDAESolve fails to converge during the first time step you can use
StartingStepSize to specify a smaller value for the initial integration step size. The default setting
is StartingStepSize −> Automatic, which means StartingStepSize ⩵/t t / .
StepSizeFactor
To reduce computation time and increase simulation accuracy NDAESolve employs an automatic step
size control scheme. If the estimated simulation error in between two integration time steps is very
low then the step size is increased. On the other hand, if the estimated error is too large the step
size is cut back. Increasing and reducing the step size is performed by multiplying or dividing the
current step size by a factor given by the value of the option StepSizeFactor. The default setting
is StepSizeFactor −> 1.5.
2.7.5 Transient Analysis with Initial Conditions
Circuits with Initial Conditions
The handling of initial conditions was rather complicated with version 1 of Analog Insydes.
Therefore, the netlist format was extended to treat initial conditions of dynamic circuit elements
such as capacitors or inductors. This is done by specifying the setting InitialCondition −> value
in the option field of the particular netlist entry (see Section 3.1.4).
Consider the RLC circuit shown in Figure 7.4. The initial voltage V C1 across the capacitor C1 at t ⩵
is given as V C1 ⩵ V ic . Assume that the following numerical values are given for the circuit elements:
R1 ⩵ , L1 ⩵ ΜH, C1 ⩵ ΜF, and Vic ⩵ mV.