1## libCEED + Nek5000 Examples 2 3### Prerequisites 4 5Nek5000 v18.0 or greater must be [installed](https://nek5000.mcs.anl.gov/getstarted/) to run 6these examples. It is assumed to exist at `../../../Nek5000` (a sibling to the 7libCEED directory) or at a path defined in the environment variable `NEK5K_DIR`. 8For example, you could set 9```sh 10 export NEK5K_DIR=/scratch/Nek5000 11``` 12if that is where it is located. 13 14The Nek5000 examples depend on the Nek5000 tools: `genbox`, `genmap`, 15and `reatore2`. They can be built using 16```sh 17 ( cd $NEK5K_DIR/tools && ./maketools genbox genmap reatore2 ) 18``` 19See also the [Nek5000 documentation](https://nek5000.mcs.anl.gov/getstarted/). 20 21### Building the Nek5000 examples 22 23You can build the Nek5000 libCEED examples with the command `make bps`. 24 25You can also build the Nek5000 libCEED examples by invoking `nek-examples.sh` script. 26```sh 27 ./nek-examples.sh -m 28``` 29 30By default, the examples are built with MPI. To build the examples without MPI, 31set the environment variable `MPI=0`. 32 33Note: Nek5000 examples must be built sequentially. Due to the Nek5000 build 34process, multiple examples cannot be built in parallel. At present, there is 35only one Nek5000 example file to build, which handles both CEED BP 1 and 36CEED BP 3. 37 38### Running Nek5000 examples 39 40You can run the Nek5000 libCEED examples by invoking `nek-examples.sh` 41script. The syntax is: 42```sh 43 ./nek-examples.sh -c <ceed_backend> -e <example_name> \ 44 -n <mpi_ranks> -b <box_geometry> 45``` 46The different options that can be used for the script are listed below: 47``` 48options: 49 -h|-help Print this usage information and exit 50 -c|-ceed Ceed backend to be used for the run (optional, default: /cpu/self) 51 -e|-example Example name (optional, default: bp1) 52 -n|-np Specify number of MPI ranks for the run (optional, default: 1) 53 -t|-test Run in test mode (not on by default) 54 -b|-box Box case in boxes sub-directory found along with this script (default: 2x2x2) 55 -clean clean the examples directory 56 -m|-make Make the examples 57``` 58The only mandatory argument is `-b` or `-box` which sets the box geometry to be 59used. This geometry should be found in `./boxes` directory. 60 61For example, you can run bp1 as follows: 62```sh 63 ./run-nek-example.sh -ceed /cpu/self -e bp1 -n 4 -b 3 64``` 65which is the same as running: 66```sh 67 ./run-nek-example.sh -b 3 68``` 69