Page 271 - Schaum's Outline of Differential Equations
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CHAPTER        26







                          Solutions of                                    Linear




              Differential                                  Equations




                                             with               Constant




               Coefficients                                    by Matrix




                                                                  Methods












         SOLUTION   OF THE INITIAL-VALUE    PROBLEM
            By the procedure  of Chapter  17, any initial-value problem  in which the differential equations  are all linear
         with constant coefficients,  can be reduced  to the matrix system




         where A is a matrix of constants. The  solution  to Eq.  (26.1)  is




         or equivalently




         In particular,  if  the initial-value  problem  is homogeneous  [i.e., f(t) = 0],  then  both  equations  (26.2)  and  (26.3)
         reduce  to



                                                                                  At
                                                        A< s)
                                           (>
            In the above solutions, the matrices  e^  '°\e  As , and e -'  are easily computed  from  e  by replacing  the
         variable  t by t -  t 0, -s,  and t — s, respectively.  Usually  x(t) is obtained  quicker  from  (26.3)  than from  (26.2),
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