toms243, a Python code 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: or NETLIB:


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.

Related Data and Programs:

TEST_VALUES, a Python code which tabulates several values of a variety of special functions.


  1. David Collens,
    Algorithm 243: Logarithm of a Complex Number,
    Communications of the Association for Computing Machinery,
    Volume 7, Number 11, November 1964, page 660.

Source Code:

Last revised on 05 January 2019.