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2.2 Netlists 43
The result represents the Laplace transform of the zero-state response of the voltage at node 2,
expressed in terms of the complex frequency variable s.
The zero-state response is the response of a system which was in the zero state at the time just prior to the
application of the input signal. Zero state means that all initial conditions, i.e. capacitor voltages and inductor
currents, are zero.
2.2.4 More about Netlists
The General Value-Field Format
As indicated in the previous section, some aspects regarding the netlist format have not yet been
mentioned. So far, we have used only the simplest form of writing netlist entries (see Section 2.2.1).
In general, however, the value field of a netlist entry does not need to be a single Mathematica
expression but may also be a nonempty sequence of options. Netlist entries may thus look like this:
{name, {nodes}, option 1 −> value 1 , option 2 −> value 2 , }
There are several value-field option keywords which Analog Insydes understands (see Section 3.1.4):
Value, Symbolic, Type, Pattern, InitialCondition, Model (Section 3.2.1), and Subcircuit
(Section 3.2.2). Their meanings will be discussed in the following subsections.
Value
If the value field is written in its general sequence-of-options form then all of its components must be
options. This necessitates an option which specifies the value of the circuit element, namely Value
(see Section 3.1.4). With the Value option we can rewrite a netlist entry such as
{R1, {1, 2}, R1}
in the following semantically equivalent general form:
{R1, {1, 2}, Value −> R1}
Of course, as long as the value field contains no more information than only the element value the
simple form is the preferred form. Note that if the value field is written in option form, then the
Value option must be present.
Symbolic
The Symbolic option (see Section 3.1.4) is closely related to the Value option. It allows you to
specify an alternative symbolic element value in addition to a numerical value given as argument to
the Value option, for instance:
{R1, {1, 2}, Value −> 100, Symbolic −> R1}
By default, circuit equations are set up using the arguments of the Value options as element values,
but CircuitEquations (Section 3.5.1) can be instructed to use the symbolic values instead wherever