1# libCEED: Examples 2 3This page provides a brief description of the examples for the libCEED library. 4 5## Example 1 6 7This example uses the mass matrix to compute the length, area, or volume of a 8region, depending upon runtime parameters. 9 10## Bakeoff Problems 11 12This section provides a brief description of the bakeoff problems, used as examples 13for the libCEED library. These bakeoff problems are high-order benchmarks designed 14to test and compare the performance of high-order finite element codes. 15 16For further documentation, readers may wish to consult the 17[CEED documentation](http://ceed.exascaleproject.org/bps/) of the bakeoff problems. 18 19### Bakeoff Problem 1 20 21Bakeoff problem 1 is the *L<sup>2</sup>* projection problem into the finite element space. 22 23The supplied examples solve *_B_ u = f*, where *_B_* is the mass matrix. 24 25### Bakeoff Problem 2 26 27Bakeoff problem 2 is the *L<sup>2</sup>* projection problem into the finite element space on a vector system. 28 29The supplied examples solve *_B_ _u_ = f*, where *_B_* is the mass matrix. 30 31### Bakeoff Problem 3 32 33Bakeoff problem 3 is the Poisson problem. 34 35The supplied examples solve *_A_ u = f*, where *_A_* is the Poisson operator. 36 37### Bakeoff Problem 4 38 39Bakeoff problem 4 is the Poisson problem on a vector system. 40 41The supplied examples solve *_A_ _u_ = f*, where *_A_* is the Poisson operator. 42 43## Navier-Stokes Solver 44 45The Navier-Stokes problem solves the compressible Navier-Stokes equations using an explicit time integration. 46 47## Running Examples 48 49To build the examples, set the `MFEM_DIR`, `PETSC_DIR` and `NEK5K_DIR` variables 50and run: 51 52```console 53# libCEED examples on CPU and GPU 54cd ceed 55make 56./ex1 -ceed /cpu/self 57./ex1 -ceed /gpu/occa 58cd ../.. 59 60# MFEM+libCEED examples on CPU and GPU 61cd mfem 62make 63./bp1 -ceed /cpu/self -no-vis 64./bp1 -ceed /gpu/occa -no-vis 65cd ../.. 66 67# PETSc+libCEED examples on CPU and GPU 68cd petsc 69make 70./bps -problem bp1 -ceed /cpu/self 71./bps -problem bp1 -ceed /gpu/occa 72cd ../.. 73 74cd navier-stokes 75make 76./navierstokes -ceed /cpu/self 77./navierstokes -ceed /gpu/occa 78cd ../.. 79 80# Nek+libCEED examples on CPU and GPU 81cd nek5000 82./make-nek-examples.sh 83./run-nek-example.sh -ceed /cpu/self -b 3 84./run-nek-example.sh -ceed /gpu/occa -b 3 85cd ../.. 86``` 87 88The above code assumes a GPU-capable machine with the OCCA backend 89enabled. Depending on the available backends, other Ceed resource specifiers can 90be provided with the `-ceed` option. 91