DM: Interfacing Between Solvers and Models/Discretizations# DM Basics PetscSection: Connecting Grids to Data General concept Multiple Fields Working with data Global Sections: Constrained and Distributed Data Permutation: Changing the order of array data DMPlex Specific Functionality: Obtaining data from the array DMPlex: Unstructured Grids Representing Unstructured Grids Grid Point Orientations Dealing with Periodicity Connecting Grids to Data Using PetscSection: Data Layout using DMPLEX and PetscFE Partitioning and Ordering Evaluating Residuals Saving and Loading DMPlex Data with HDF5 Metric-based mesh adaptation DMSTAG: Staggered, Structured Grid Terminology Working with vectors and operators (matrices) Coordinates Numberings and internal data layout Networks Application flow Utility functions Retrieving components and number of variables PetscDT: Discretization Technology in PETSc Quadrature Probability Distributions PetscFE: Finite Element Infrastructure in PETSc Using Pointwise Functions to Specify Finite Element Problems Describing a particular finite element problem to PETSc Assembling finite element residuals and Jacobians