Example 1

                                  | 0,  0<=t<5
 Example 1: solve 2y" + y' + 2y = | 1,  5<=t<20
                                  | 0,  20<=t
            u(0) = 0; u'(0) = 0

Example 2

   
                            | 0,        0<=t<5
 Example 2: solve y" + 4y = | (t-5)/5,  5<=t<10
                            | 1,        10<=t
            u(0) = 0; u'(0) = 0