Fast Matrix Based Computation of Eigenvalues in PolSAR Data

We describe calculation of eigenvalues of 2×2 and 3×3 Hermitian matrices as used in the analysis of multilook polarimetric SAR data. The eigenvalues are calculated as the roots of quadratic or cubic equations. The methods are well suited for fast matrix oriented computer implementation and we obtain speed-ups over calculations based on a built-in eigenproblem solver in for-loops over rows and columns in an image by a factor of 350 (for dual pol) and 175 (for full/quad pol).