ecTrans

ecTrans is the global spherical Harmonics transforms library, extracted from the IFS. It is using a hybrid of MPI and OpenMP parallelisation strategies. The package contains both single- and double precision Fortran libraries (trans_sp, trans_dp), as well as a C interface to the double-precision version (transi_dp)

Trans is distributed under the Apache License Version 2.0. See LICENSE file for details.

• Linux
• Apple MacOS

Other UNIX-like operating systems may work too out of the box.

• Fortran compiler with OpenMP support
• C compiler
• FIAT (see https://github.com/ecmwf-ifs/fiat )
• ecBuild (see https://github.com/ecmwf/ecbuild)
• CMake (see https://cmake.org)
• A BLAS library

Further optional recommended dependencies:

• FFTW (http://www.fftw.org)

Building and installing Trans happens via CMake, which provides automatic detection for third-party libraries in standard locations and helps cross-plaform portability. There are multiple ways to help CMake discover packages in non-standard locations. One explicit way is to e.g. set environment variables for each dependency.

Environment variables

$ export ecbuild_ROOT=<path-to-ecbuild>
$ export fiat_ROOT=<path-to-fiat>
$ export CC=<path-to-C-compiler>
$ export FC=<path-to-Fortran-compiler>

You must compile FIAT out-of-source, so create a build-directory (anywhere)

$ mkdir build && cd build

Configuration of the build happens through standard CMake

$ cmake

Extra options can be added to the cmake command to control the build:

• -DCMAKE_BUILD_TYPE=<Debug|RelWithDebInfo|Release|Bit> default=RelWithDebInfo (typically -O2 -g)
• -DENABLE_TESTS=<ON|OFF> default=ON
• -DENABLE_SINGLE_PRECISION=<ON|OFF> default=ON
• -DENABLE_DOUBLE_PRECISION=<ON|OFF> default=ON
• -DENABLE_TRANSI=<ON|OFF> default=ON
• -DENABLE_MKL=<ON|OFF> default=ON
• -DCMAKE_INSTALL_PREFIX=<install-prefix>

More options to control compilation flags, only when defaults are not sufficient

• -DCMAKE_Fortran_FLAGS=<fortran-flags>
• -DCMAKE_C_FLAGS=<c-flags>

Once this has finished successfully, run make and make install.

Optionally, tests can be run to check succesful compilation, when the feature TESTS is enabled (-DENABLE_TESTS=ON, default ON)

$ ctest

TODO

TODO