1## libCEED + Nek5000 Examples 2 3### Prerequisites 4 5Nek5000 v19.0 or greater must be [installed](https://nek5000.mcs.anl.gov/getstarted/) to run these examples. 6It is assumed to exist at `../../../Nek5000` (a sibling to the libCEED directory) or at a path defined in the environment variable `NEK5K_DIR`. 7For example, you could set 8```sh 9 export NEK5K_DIR=/scratch/Nek5000 10``` 11if that is where it is located. 12 13The Nek5000 examples depend on the Nek5000 tools: `genbox`, `genmap`, and `reatore2`. 14They can be built using 15```sh 16 ( cd $NEK5K_DIR/tools && ./maketools genbox genmap reatore2 ) 17``` 18See also the [Nek5000 documentation](https://nek5000.mcs.anl.gov/getstarted/). 19 20### Building the Nek5000 examples 21 22You can build the Nek5000 libCEED examples with the command `make bps`. 23 24You can also build the Nek5000 libCEED examples by invoking `nek-examples.sh` script. 25```sh 26 ./nek-examples.sh -m 27``` 28 29By default, the examples are built with MPI. 30To build the examples without MPI, set the environment variable `MPI=0`. 31 32Note: Nek5000 examples must be built sequentially. 33Due to the Nek5000 build process, multiple examples cannot be built in parallel. 34At present, there is only one Nek5000 example file to build, which handles both CEED BP 1 and CEED BP 3. 35 36### Running Nek5000 examples 37 38You can run the Nek5000 libCEED examples by invoking `nek-examples.sh` script. 39The syntax is: 40```sh 41 ./nek-examples.sh -c <ceed_backend> -e <example_name> \ 42 -n <mpi_ranks> -b <box_geometry> 43``` 44The different options that can be used for the script are listed below: 45``` 46options: 47 -h|-help Print this usage information and exit 48 -c|-ceed Ceed backend to be used for the run (optional, default: /cpu/self) 49 -e|-example Example name (optional, default: bp1) 50 -n|-np Specify number of MPI ranks for the run (optional, default: 1) 51 -t|-test Run in test mode (not on by default) 52 -b|-box Box case in boxes sub-directory found along with this script (default: 2x2x2) 53 -clean clean the examples directory 54 -m|-make Make the examples 55``` 56The only mandatory argument is `-b` or `-box` which sets the box geometry to be used. 57This geometry should be found in `./boxes` directory. 58 59For example, you can run bp1 as follows: 60```sh 61 ./run-nek-example.sh -ceed /cpu/self -e bp1 -n 4 -b 3 62``` 63which is the same as running: 64```sh 65 ./run-nek-example.sh -b 3 66``` 67