toms443, a MATLAB code which evaluates Lambert's W function. This is a version of ACM TOMS algorithm 443, by Fritsch, Shafer and Crowley.
Lambert's W function W(X) satisfies the equation
W(x) * exp ( W(x) ) = x
The text of many ACM TOMS algorithms is available online through ACM: https://calgo.acm.org/ or NETLIB: https://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.
toms443 is available in a C version and a C++ version and a FORTRAN90 version and a MATLAB version.
test_values, a MATLAB code which contains routines which return sample values of various functions, including the modified beta function, and the logarithm of the gamma function.
toms743, a MATLAB code which evaluates lambert's w function. this is a version of acm toms algorithm 743, by barry, barry and culligan-hensley.