Tutorial: From Zero to Devito

Rhodri Nelson

What you'll need:
Slack channel: #t22-tue-devito (visit https://softwareunderground.org/slack to join)
Repo: https://github.com/devitocodes/transf...

Devito is a domain specific language (DSL) and compiler for finite difference schemes. Built on top SymPy, the DSL allows users to express PDE boundary value problems in a few lines of Python code. This workshop will introduce attendees to the core elements of the Devito DSL with a focus on modelling seismic wave-propagation. A breakdown of the agenda is as follows:

Introduction to the DSL - Expressing PDEs in Devito
Introduction to Devito operators
Building wave-propagators
Full waveform inversion with Devito

TIMESTAMPS

00:00:00 Software Underground Info
00:02:02 Intro to tutorial
00:06:34 Part 1: The Devito DSL - From equations to code in a few lines of Python
00:08:03 Defining the physical domain
00:10:09 Functions and data
00:21:49 Forming finite difference schemes
00:35:25 Second derivatives and high-order stencils
00:44:19 Derivatives of composite expressions
00:45:15 Break
00:54:30 Part 2: Introduction to seismic modelling - 2D acoustic propagator
00:55:45 Modelling workflow
00:57:54 The acoustic seismic wave equation
00:59:10 Finite domains
01:00:49 Seismic modelling with devito
01:05:25 Acquisition geometry
01:16:52 Finite-difference discretization
01:19:51 Source injection and receiver interpolation
01:21:49 Devito operator and solve
01:24:30 Break
01:30:34 Part 3: Full-Waveform Inversion (FWI)
01:33:44 Imaging with back-propagation
01:33:45 The Objective Function
01:34:48 Local Inversion
01:35:40 Steepest Descent
01:37:22 Calculating the gradient
01:38:58 Interpreting the expression for the gradient
01:41:58 True and smooth velocity models
01:48:28 FWI gradient operator
01:57:47 Final remarks