pbdl-book/notation.md

Notation and Abbreviations

Math notation:

Symbol	Meaning
A	matrix
\eta	learning rate or step size
\Gamma	boundary of computational domain \Omega
f^{*}	generic function to be approximated, typically unknown
f	approximate version of f^{*}
\Omega	computational domain
\mathcal P^*	continuous/ideal physical model
\mathcal P	discretized physical model, PDE
\theta	neural network params
t	time dimension
\mathbf{u}	vector-valued velocity
x	neural network input or spatial coordinate
y	neural network output

Summary of the most important abbreviations:

ABbreviation	Meaning
CNN	Convolutional Neural Network
DL	Deep Learning
GD	(steepest) Gradient Descent
MLP	Multi-Layer Perceptron, a neural network with fully connected layers
NN	Neural Network (a generic one, in contrast to, e.g., a CNN or MLP)
PDE	Partial Differential Equation
PBDL	Physics-Based Deep Learning
SGD	Stochastic Gradient Descent

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