# Installation¶

## Requirements¶

Bempp-cl can be installed on any Windows, Mac, or Linux system with Python 3.7. The following dependencies are required:

• numpy

• scipy

• numba

• pyopencl

• meshio

• plotly

## OpenCL¶

Bempp-cl uses OpenCL kernels to launch computations. OpenCL is a standard for accessing various types of compute devices, including CPUs and GPUs. Bempp-cl uses OpenCL to compile C99 kernels during runtime for the underlying compute device. This requires a runtime environment to be installed. Runtime environments are available from Apple (CPU, GPU), Nvidia (GPU), AMD (GPU) <https://rocm.github.io/install.html>_, Intel (CPU/GPU) and through the open-source Pocl Project (CPU). In the following a few important remarks about OpenCL runtime environments.

• Most GPU devices are much faster in single precision and we do not advise using Bempp in double precision on such devices.

• If Pocl is used we require at least version 1.3. The package in the current Ubuntu 18.04 LTS release is older and does not yet support Bempp-cl.

• The Apple CPU runtime environment is not compatible with Bempp-cl.

We provide quick installation instructions with Pocl, but also test regularly with AMD and Nvidia runtime environments. This quick installation creates a working installation based on the Pocl ICD (Installable Client Driver). For the activation of other ICDs (e.g. from AMD or Nvidia) see further below.

## Quick-Installation¶

The quick installation gets you up and running on a CPU based system. It works on Mac OS, Linux and the Windows Subsystem for Linux. The only requirement is a working conda installation.

First, if not already done, enable the conda-forge channel.

conda config --add channels conda-forge
conda config --set channel_priority strict


Next, create a new environment for Bempp and change into it.

conda create -n bempp python=3.7
conda activate bempp


We are using Python 3.7 by default, as there is currently still a bug with Numba and Python 3.8 that effects Bempp-cl. On older versions of conda it may be necessary to use source activate instead of conda activate.

We can now install Bempp-cl with

conda install bempp-cl


This installs Bempp-cl with a minimal set of dependencies that are required to run the software. However, we strongly recommend to also install Gmsh, Matplotlib, and Jupyter. This can be done via

conda install gmsh matplotlib jupyter


## Using other compute devices¶

Any compute device that provides a valid ICD can in principle be used with Bempp. However, if Bempp is installed within a conda environment these may not be seen by the installation. The reason is that conda expects files in different locations than may be provided by the system. The following two solutions have been tested on Linux based systems.

### Set the ICD location via environment variable¶

Typically, GPU vendors install ICDs in /etc/OpenCL/vendors. You can set this as default search path for ICD files with the command

export OPENCL_VENDOR_PATH=/etc/OpenCL/vendors


The drawback is that as long as this variable is set the Pocl driver provided through conda is not visible any more.

### Copy ICD files into the correct location¶

An alternative to setting an environment variable is to copy the system ICD files into a location that conda knows.

First, find out where your conda environment is installed, using e.g. the command which python when the environment is active. The output of the command may be something like

/home/user/miniconda3/envs/bempp/bin/python


But this depends on whether Anaconda Python or Miniconda is installed and where the base installation resides. The directory in which conda installs ICDs is

/home/user/miniconda3/envs/bempp/etc/OpenCL/vendors


This directory already contains a file called pocl.icd which has been installed through the pocl conda package. To use other ICD drivers copy them over from the system directory /etc/OpenCL/vendors into the above directory of your conda environment.