43 Note that for the matrix inverses given in (3-11) to exist, conditions (1), (2), and (3) are needed. In addition, if H[xl F]~*G is not square, any right inverse can be used. We shall make use of the following formula which can be obtained using a partial fraction expansion Csl-F]"1 (s-X)' N i - { I (-1)J j=l L[AI-F]"j- (S-A) N+l-j + ( [sI-F]-1 [F-AirN } (3-13) where it is assumed that A is not an eigenvalue of F. Using (3-13) and (3-10) it is then possible to write (3-5) as R*(s) = HCSI-F]-1 { x* + [F-A^rtw + [F-A1I]"2Gv + [F-A^l'V } t + H[X1I-F]_1Sv^-i- HCAjI-F^Gv^ T (3-14) When (3-11) and (3-12) are substituted into (3-14) we obtain the desired k . R (s). It also follows from (3-4), (3-10), and (3-12) that the X*(s) which occurs during tracking can be expressed as X*(s) = [A1I-F]"1Gwtilrr + [A1I-F]1Gvy-^- ^ (s-Aj) -,-2... 1 1 - [A.I-F]" Gv-^y-y + [A2I-F]-GrT^x-T (3-15)