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80 2. Tutorial
2.4.4 Additional Options for CircuitEquations
All Analog Insydes options which have an influence on circuit equation setup by the function
CircuitEquations can be accessed through Options[CircuitEquations]. The current option
settings can be inspected by retrieving the value of this variable:
In[14]:= Options[CircuitEquations]
Out[14]=
AnalysisMode AC, BranchCurrentPrefix I$,
BranchVoltagePrefix V$, ControllingCurrentPrefix IC$,
ControllingVoltagePrefix VC$, ConvertImmittances True,
DefaultSelector Automatic, DesignPoint Automatic,
ElementValues Value, Formulation ModifiedNodal,
FrequencyVariable s, IgnoreMissingGround False,
IndependentVariable Automatic, InitialConditions None,
InitialGuess Automatic, InitialTime 0,
InstanceNameSeparator InheritedAnalogInsydes,
LibraryPath InheritedAnalogInsydes, MatrixEquation True,
ModelLibrary InheritedAnalogInsydes, ModeValues None,
NodeVoltagePrefix V$, Protocol InheritedAnalogInsydes,
Symbolic All, TimeVariable t, Value None
Some of these options are discussed in more detail below.
AnalysisMode
CircuitEquations sets up circuit equations for the analysis modes AC, DC, and transient. Which
mode to use is determined by the option AnalysisMode, whose value is one of the symbols AC, DC,
and Transient. The default value is AC. Up to now, we used CircuitEquations to create smallsignal
equations. Section 2.6.4 describes how to set up DC equations and Section 2.7.1 describes how
to set up transient equations.
MatrixEquation
Using the option MatrixEquation −> False, we can force CircuitEquations not to use a matrix
representation when setting up small-signal circuit equations but to return a list of scalar equations
instead.
In[15]:= CircuitEquations[rlcfilter,
MatrixEquation −> False] // DisplayForm
Out[15]//DisplayForm=
V$1 V$2
V$1 V$2 V$2 V$3
I$V0
⩵⩵ 0, C1 s V$2
⩵⩵ 0,
RA
RA
L1 s
V$3
V$2 V$3
C2 s V$3
⩵⩵ 0, V$1 ⩵⩵ V0,
RB L1 s
V$1, V$2, V$3, I$V0, DesignPoint
When the matrix representation is turned off, the value returned by CircuitEquations is a
DAEObject containing the circuit equations as a list of two elements, the first being the system of
circuit equations and the second the vector of unknowns. The advantage of the scalar representation
is that it consumes less memory than the matrix representation because Mathematica does not have