Configuration and Dependencies#

Tip

pressio is header-only, so it does not need to be precompiled and linked to.

Warning

To use pressio, you need at least a C++17 compiler.

Dependencies#

Some parts of pressio contain code and implementations that are specific to third-party libraries (TPLs). The main reason for doing this is that we aim, where possible, to alleviate the user from writing custom operations and allow pressio to decide when and how to leverage the native libraries’ operations to obtain the best performance. This should facilitate the integration and use of pressio by existing applications. This is a growing capability and we currently only provide built-in support to some external HPC libraries (see below). Obviously, these TPLs-specific specializations need to be guarded with preprecessor directives, and enabled only if one can access the TPLs.

Enabling/disabling specific dependencies can be done by defining the macros listed here. When building the tests, these macros can also be set during configuration with cmake.

Optional vs Required#

TPL Name

Optional/Required

Version Known to Work/run in CI

Eigen

Required

3.4.0

Trilinos

Optional

commits: 0dc4553, 5bbda25

MPI

Optional

–

Kokkos

Optional

4.4.01

BLAS

Optional

–

LAPACK

Optional

–

GoogleTest

Optional

1.14.0

Eigen is the only required dependency because it is the default choice for instantiating the ROM data structures and solving the (dense) ROM problem.

In practice, what are the steps to get and use Pressio?#

1. Clone pressio (defaults to the main branch), or you can pick a release version

  1. Clone pressio-ops and, optionally, pressio-log

  2. Add the pressio/include, pressio-ops/include, and (optionally) pressio-log/include to your project’s include directories.

  3. Use the Pressio library

Before including any Pressio files, be sure to identify any third-party dependencies as discussed above. You can define macros to enable or disable code related to these dependencies.

The following code enables the MPI and Kokkos libraries, and activates the Pressio logger.

#define PRESSIO_ENABLE_TPL_MPI 1
#define PRESSIO_ENABLE_LOGGER 1
#define PRESSIO_ENABLE_TPL_KOKKOS 1

#include "pressio/what_you_need.hpp"
// ...
int main() {
 // do something
}

When enabling TPLs with the macros above, pressio does not need to know where a target TPL exists in your system. By setting the macro, you are simply telling Pressio that you have a certain TPL and want to enable the corresponding code in pressio. The TPLs will be needed at linking stage when you build your code that uses pressio.

Tip

More information regarding the Pressio logger, including macros and configuration details, can be found in the README.

Testing#

The following steps explain how to build and runs the Pressio tests.

  1. Begin by cloning pressio.

Tip

You do not need to explicitly clone pressio-ops, as it will be included automatically when the tests are built.

Similarly, pressio-log is included automatically if the PRESSIO_ENABLE_LOGGING CMake variable is turned on.

  1. Create a build directory.

cd <where-you-cloned-pressio>
mkdir build && mkdir install

  1. Use cmake to configure by passing to the command line the target list of CMake variables to define.

For example, suppose we want to enable support for Trilinos and the logger. We would do:

export PRESSIO_SRC=<where-you-cloned-pressio>
cd <where-you-cloned-pressio>/build

cmake -D PRESSIO_ENABLE_TPL_TRILINOS=ON \
      -D PRESSIO_ENABLE_LOGGING=ON \
      -D PRESSIO_ENABLE_TESTS=ON \
      ${PRESSIO_SRC}

make # tests are built

Note that this step only builds tests because pressio is header-only. If you want, inspect the file <where-you-cloned-pressio>/install/pressio_cmake_config.h which contains the CMake variables configuration.

By default, this step will also clone and link to the Pressio/pressio-ops library, which contains essential operations for pressio.

Tip

Since the tests assume the role of an application using pressio, they will need to link against any TPLs that you enable. To specify the location of a library, use the following CMake variable: -D <tpl>_DIR=/path/to/tpl/install.

  1. Run the tests

cd <where-you-cloned-pressio>/build
ctest -j <np>