Changed invert from (numerically instable and practically unusable) non-pivoting Gauss-Seidel to a QR decomposition.
Changed invert from (numerically instable and practically unusable) non-pivoting Gauss-Seidel to a QR decomposition.

tkemmer/ball,tkemmer/ball,tkemmer/ball,tkemmer/ball,tkemmer/ball,tkemmer/ball