An improved covariance matrix encoding scheme wherein a covariance matrix
is described in terms of Euler angles and eigenvalues. A covariance
matrix, P, is decomposed into its eigenvalues and eigenvectors. The
eigenvalues and their corresponding eigenvectors are arranged starting
with the smallest value, and the next two ordered such that, the
eigenvector set comprises a right-handed coordinate system. Each
eigenvalue is then encoded with a logarithmic or other compression
scheme. Euler angles are calculated and angle is compressed and an offset
is added to each angle. The covariance matrix is then reconstructed from
the encoded values to test if the encoded matrix completely covers the
original matrix. If necessary, a scale factor is applied to all
reconstructed eigenvalues and the scaled versions are then re-encoded as
described above. The scaling and re-encoding process ensures that the
encoded matrix covers the original matrix.