This is the source code repository for ERFA (Essential Routines for Fundamental Astronomy). ERFA is a C library containing key algorithms for astronomy, and is based on the SOFA library published by the International Astronomical Union (IAU).
ERFA is intended to replicate the functionality of SOFA (aside from possible
bugfixes in ERFA that have not yet been included in SOFA), but is licensed
under a three-clause BSD license to enable its compatibility with a wide
range of open source licenses. Permission for this release has been
obtained from the SOFA board, and is avilable in the LICENSE
file included
in this source distribution.
This version of ERFA (v1.3.0) is based on SOFA version "20160503_a", with the differences outlined below.
All references to "SOFA" in the source code have been changed to ERFA, and
functions have the prefix era
instead of iau
.
All C macros used in ERFA are the same as their SOFA equivalents, but with an
ERFA_
prefix to prevent namespace collisions.
ERFA includes smaller changes that may or may not eventually make it into SOFA, addressing localized bugs or similar smaller issues:
- ERFA 1.4.0 and SOFA "20170420"
- ERFA 1.4.0 adds the
eraVersion
anderaSofaVersion
functions to determine the installed version of ERFA (and the SOFA version it is derived from). - ERFA 1.4.0 includes some bug fixes contributed to ERFA after 1.3.0 but before 1.4.0. These were incorporated (with modification) into SOFA "20170420" (without attribution) and hence these are not differences between ERFA and SOFA. (See liberfa#40 and liberfa#41)
- ERFA 1.4.0 adds the
- ERFA 1.3.0 and SOFA "20160503_a"
- There are no differences between ERFA 1.3.0 and SOFA "20160503_a".
- ERFA 1.2.0 and SOFA "20150209_a"
- Typos have been corrected in the documentation of atco13 and atio13 (see liberfa#29).
Note that issues identified in ERFA should generally also be reported upstream to SOFA at [email protected].
To build and install a released version of ERFA in your OS's standard location, simply do:
./configure make make install
If you want to run the tests to make sure ERFA built correctly, before installing do:
make check
If you are using a developer version from github, you will need to first do
./bootstrap.sh
before the above commands. This requires autoconf
and
libtool
.
If you wish to build against the ERFA static library without installing, you
will find it in $ERFAROOT/src/.libs/liberfa.a
after running make
.
Alternatively, if you wish to bundle the ERFA source code with a separate
package, you can use the source_flattener.py
script from the
erfa-fetch repository to combine
the ERFA source code into just two files: a erfa.c
source file, and an
erfa.h
include file. You should run this script like this:
cd /path/to/erfa-source-code python /path/to/erfa-fetch/source_flattener.py src -n erfa
If possible, however, it is recommended that you provide an option to use any copy of the ERFA library that is already installed on the system.