Hi,
I'm playing with DSolve and would like to solve a vector equation with boundary conditions. Say I have a simple equation like this:

deq = m r''[t] == m a

Now I want r and a to be vectors and solve deg for some boundary conditions r[0]={0,1} and r'[0]={1,1}. This should be easy but I don't know how to tell Matematica (v10). I tried this, but it's not working:

DSolve[{deq, r[0] == {0, 1}, r'[0] == {1, 1}}, {r[t]}, {t}]
DSolve::bvnul: For some branches of the general solution, the given boundary conditions lead to an empty solution. >>

So, whats the right way to do it?

Flo

Edit: 'Manually' writing down the two equations works, but it's not exactly elegant:

In[1]:= deq = {m rx''[t] == m ax, m ry''[t] == m ay};
        DSolve[{deq, rx[0] == 0, ry[0] == h, rx'[0] == vx, ry'[0] == vy}, {rx[t], ry[t]}, {t}]
Out[2]= {{rx[t] -> 1/2 (ax t^2 + 2 t vx), ry[t] -> 1/2 (2 h + ay t^2 + 2 t vy)}}