Glossary

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This page contains a glossary of terms related to the MORB database, the Search Tool, and this wiki as a whole.

Note that all boolean fields are really quadruple valued; in addition to 0 (false) and 1 (true), other options include the following:

• an empty field, indicating a lack of knowledge, e.g., either no attempt has been made to figure out the value, or none of the available methods have been successful in determining the value thus far.
• NaN, indicating either that the property does not apply or is otherwise impossible to determine

Abbreviation / Attribute / Term	Description
comments	(char) internal comments
dataSource	(char) where the data was pulled from during processing: unimat, rommes, or morwiki
sourceFilename	(char) filename of data used during processing
AP	affine parametric; parameters of any component are linear combinations of fixed matrices
components	(char) matrices stored in .mat file; see also Models
cond*	(list of float) the numerically computed ratio between the largest and smallest singular values of the matrix * (including 0); Inf is treated as a float in MATLAB; note that AP systems will have a list of floats, with each entry pertaining to the matrix of the same index
benchmarkCreator	(list of char) ORCID(s) of original author(s) or creator(s) of dataset
DAE	differential algebraic equation
daeDiffIndex	(int) DAE differentiation index; roughly the number of differentiations required to make a system an ODE
DEIM	discrete empirical interpolation method
category	(char) folder / collection to which a benchmark belongs
DoF	degrees of freedom
DSPMR	dominant subspace projection model reduction
dataEditor	(list of char) ORCID(s) of editor(s) who converted data to new .mat format
FEM	finite element method
filename	(char) filename and benchmark ID
FOM	full order model
FOS	first-order system
is*CholAble	(list of bool) the matrix * is symmetric positive definite, i.e., it admits a Cholesky factorization (and is therefore "Cholesky-able"); note that AP systems will have a list of floats, with each entry pertaining to the matrix of the same index
is*Sparse	(list of bool) the matrix * is stored in a sparse format; note that AP systems will have a list of floats, with each entry pertaining to the matrix of the same index
is*Symm	(list of bool) the matrix is symmetric; note that AP systems will have a list of floats, with each entry pertaining to the matrix of the same index
isContractive	(bool) a system that is dissipative w.r.t. $s(u(t),y(t)) = ||u(t)||^2 - ||y(t)||^2$
isDAE	(bool) differential algebraic equation; an LTI DAE has a nonzero, singular E component
isPassive	(bool) a system that is dissipative w.r.t s(u(t),y(t)) = u(t)^T y(t)
isSquare	(bool) nInputs = nOutputs
isStable	(int) numerically computed; 0 = no stability 1 = asymptotically stable; i.e., all finite eigenvalues of the pencil $sE-A$ ($E = I$, if not otherwise specified) have negative real part; consequently, the solution of the corresponding LTI with $u(t) = 0$ tends to 0 as $t \to \infty$ 2 = ? 3 = ? (other stability definitions added and defined as necessary)
isStateSpaceSymm	(bool) state-space symmetric: $A = A^T$, $C = B^T$, $E = E^T$, $D = D^T$; trivially implies isSysSymm; similarly defined for SOS, but require instead that $M = M^T$, $C_v = 0, C_p = B^T$, and $K = K^T$
isSysSymm	(bool) $H(s) = C (sE -A)^{-1} B+D$ is symmetric; equivalently, the system's Markov parameters are symmetric For a distinction between symmetry and state-space symmetry, see Def 2.1 in this paper. Another useful source
license	(char) license associated to data
LTI	linear time-invariant
LTV	linear time-varying
MIMO	multiple-input, multiple-output
MOR	model order reduction
MORWikiLink	(char) link to MORWiki page
MORWikiPageName	(char) fixed page name with plain text description of system in the MORWiki
nInputs	(int) number of inputs
NL	nonlinear; a nonlinear system depends nonlinearly on $x(t)$
nnz*	(list of int) when the matrix * is sparse, the number of nonzeros; note that AP systems will have a list of floats, with each entry pertaining to the matrix of the same index
nOutputs	(int) number of outputs
nParameters	(int) maximum number of parameters in a parametric system
nStates	(int) number of states
nUnstabPoles	(int) the number of poles with nonnegative real part, computed numerically
ODE	ordinary differential equation
PDE	partial differential equation
PMOR	parametric model order reduction
POD	proper orthogonal decomposition
QBS	quadratic bilinear system
RBM	reduced basis method
ROM	reduced order model
SISO	single-input, single-output
SOS	second-order system
SVD	singular value decomposition
systemClass	(char) model realization; see also Models
zenodoDOI	(char) zenodo DOI (not the full URL!)