1*7f296bb3SBarry Smith# PETSc in a nutshell 2*7f296bb3SBarry Smith 3*7f296bb3SBarry SmithSee {any}`handson` to immediately jump in and run PETSc code. 4*7f296bb3SBarry Smith 5*7f296bb3SBarry SmithPETSc/TAO is a tool for writing, analyzing, and optimizing large-scale numerical simulations. 6*7f296bb3SBarry Smith 7*7f296bb3SBarry Smith```{image} /images/manual/library_structure.svg 8*7f296bb3SBarry Smith:align: center 9*7f296bb3SBarry Smith:alt: PETSc Structure Diagram 10*7f296bb3SBarry Smith``` 11*7f296bb3SBarry Smith 12*7f296bb3SBarry Smith## Algebraic objects 13*7f296bb3SBarry Smith 14*7f296bb3SBarry Smith- {any}`Vectors <ch_vectors>` - containers for simulation solutions, right-hand sides of linear systems, etc (`Vec`). 15*7f296bb3SBarry Smith 16*7f296bb3SBarry Smith- {any}`Matrices <ch_matrices>` - contain Jacobians and operators that define linear systems (`Mat`). 17*7f296bb3SBarry Smith 18*7f296bb3SBarry Smith - {any}`Multiple sparse and dense matrix storage formats<doc_matrix>`, 19*7f296bb3SBarry Smith - {any}`Limited memory variable metric representations<sec_matlmvm>`, 20*7f296bb3SBarry Smith - {any}`block<sec_block_matrices>` and {any}`nested<sec_matnest>` representations, 21*7f296bb3SBarry Smith - {any}`Easy, efficient matrix assembly and interface <sec_matcreate>`. 22*7f296bb3SBarry Smith 23*7f296bb3SBarry Smith- Indices - used to access portions of vectors and matrix, for example {1,2,4} or 1:10 (`IS`). 24*7f296bb3SBarry Smith 25*7f296bb3SBarry Smith## Solvers 26*7f296bb3SBarry Smith 27*7f296bb3SBarry Smith- {any}`Linear solvers<ch_ksp>` based on preconditioners (`PC`) and Krylov subspace methods (`KSP`). 28*7f296bb3SBarry Smith 29*7f296bb3SBarry Smith- {any}`Nonlinear solvers <ch_snes>` (`SNES`). 30*7f296bb3SBarry Smith 31*7f296bb3SBarry Smith- {any}`Time integrators <ch_ts>`, (ODE/PDE), explicit, implicit, IMEX, (`TS`) 32*7f296bb3SBarry Smith 33*7f296bb3SBarry Smith - Local and global error estimators 34*7f296bb3SBarry Smith - {any}`section_sa`. 35*7f296bb3SBarry Smith 36*7f296bb3SBarry Smith- {any}`Optimization <ch_tao>` with equality and inequality constraints, first and second order (Newton) methods (`Tao`). 37*7f296bb3SBarry Smith 38*7f296bb3SBarry Smith- Eigenvalue/Eigenvectors and related algorithms in the package [SLEPc](https://slepc.upv.es). 39*7f296bb3SBarry Smith 40*7f296bb3SBarry Smith## Model/Discretization Interfaces to Solvers 41*7f296bb3SBarry Smith 42*7f296bb3SBarry Smith- Simple structured grids, `DMDA`. 43*7f296bb3SBarry Smith- Staggered grids, {any}`ch_stag`, `DMSTAG`. 44*7f296bb3SBarry Smith- Unstructured grids, {any}`ch_unstructured`, `DMPLEX`. 45*7f296bb3SBarry Smith- Networks/graphs, for example the power grid, river networks, the nervous system, {any}`ch_network`, `DMNETWORK`. 46*7f296bb3SBarry Smith- Quad or octree grids, `DMFOREST`. 47*7f296bb3SBarry Smith- Particles, `DMSWARM`. 48*7f296bb3SBarry Smith 49*7f296bb3SBarry Smith:::{seealso} 50*7f296bb3SBarry SmithFor full feature list see: 51*7f296bb3SBarry Smith 52*7f296bb3SBarry Smith- {ref}`Vector table <doc_vector>` 53*7f296bb3SBarry Smith- {ref}`Matrix table <doc_matrix>` 54*7f296bb3SBarry Smith- {ref}`Linear solvers table <doc_linsolve>` 55*7f296bb3SBarry Smith- {ref}`Nonlinear solvers table <doc_nonlinsolve>` 56*7f296bb3SBarry Smith- {ref}`ODE integrators table <integrator_table>` 57*7f296bb3SBarry Smith- {ref}`Optimizers table <doc_taosolve>` 58*7f296bb3SBarry Smith- {ref}`Model/discretization interfaces to solvers table <dm_table>` 59*7f296bb3SBarry Smith::: 60*7f296bb3SBarry Smith 61*7f296bb3SBarry Smith## Utilities for Simulations/Solvers 62*7f296bb3SBarry Smith 63*7f296bb3SBarry SmithRuntime 64*7f296bb3SBarry Smith 65*7f296bb3SBarry Smith- control of the simulation via {any}`runtime options <sec_options>` 66*7f296bb3SBarry Smith- visualization of the solvers and simulation via {any}`viewers <sec_viewers>`, 67*7f296bb3SBarry Smith- {any}`monitoring <sec_kspmonitor>` of solution progress, 68*7f296bb3SBarry Smith- {any}`profiling <ch_profiling>` of the performance, 69*7f296bb3SBarry Smith- robust {any}`error handling <sec_errors>`. 70
