toms243 is a C library which evaluates the logarithm of a complex value, by David Collens. This is a version of ACM TOMS algorithm 243.
The text of many ACM TOMS algorithms is available online through ACM: http://calgo.acm.org/ or NETLIB: http://www.netlib.org/toms/index.html.
The computer code and data files described and made available on this web page are distributed under the GNU LGPL license.
TOMS243 is available in a C version and a C++ version and a FORTRAN90 version and a MATLAB version and a Python version.
test_values, a C library which tabulates several values of a variety of special functions.