asa082, a C++ library which computes the determinant of an orthogonal matrix; this is Applied Statistics Algorithm 82, by J C Gower.
The computer code and data files described and made available on this web page are distributed under the GNU LGPL license.
asa082 is available in a C version and a C++ version and a FORTRAN77 version and a FORTRAN90 version and a MATLAB version and a Python version.
Original FORTRAN77 version by J C Gower; This C++ version by John Burkardt.