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Extracting System Matrices
In this section:
• Extracting System Matrices
• Extracting State-Space Matrices
Extracting System Matrices
Extract the matrices of the COMSOL linearized system with the function mphmatrix.
To call the function mphmatrix you need to specify solver node and the list of the
system matrices to extract:
str = mphmatrix(model, <soltag>, 'out', out);
where <soltag> is the tag of the solver node used to assemble the system matrices and
out a cell array containing the list of the matrices to evaluate. The output data str
returned by mphmatrix is a MATLAB structure whose fields correspond to the
assembled system matrices.
The system matrices that can be extracted with mphmatrix is listed in the table below:
EXPRESSION
DESCRIPTION
K
Stiffness matrix
L
Load vector
M
Constraint vector
N
Constraint Jacobian
D
Damping matrix
E
Mass matrix
NF
Constraint force Jacobian
NP
Optimization constraint Jacobian (*)
MP
Optimization constraint vector (*)
MLB
Lower bound constraint vector (*)
MUB
Upper bound constraint vector (*)
Kc
Eliminated stiffness matrix
Lc
Eliminated load vector
Dc
Eliminated damping matrix
EXTRACTING SYSTEM MATRICES
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