asa082, a Fortran90 code which computes the determinant of an orthogonal matrix; this is Applied Statistics Algorithm 82, by J C Gower.
The information on this web page is distributed under the MIT license.
asa082 is available in a C version and a C++ version and a Fortran90 version and a MATLAB version and an Octave version and a Python version.
Original Fortran77 version by J C Gower; This version by John Burkardt.