proper way of posing a non-autonomous ode in mathematica?

*To*: mathgroup at smc.vnet.net*Subject*: [mg100394] proper way of posing a non-autonomous ode in mathematica?*From*: sean_incali at yahoo.com*Date*: Tue, 2 Jun 2009 06:47:14 -0400 (EDT)

Hello group, I was trying to solve a simple ODE system that has parameters that are functions of time. Then I thought about it and I'm not sure if I'm doing it right. Let's say your system is a = -k1 (t^-h) -k2 (t^-h) b b = k1 (t) a Then in mathematica, a'[t] == - k1 (t ^-h) a[t] - k2 (t ^-h) b[t], b'[t] == k1 (t ^-h) a[t] which is solvable. but if I pose the k1 and k2 as a function of t, like k1[t^-h] and k2 [t^-h] Then the system becomes under-determined with 4 unknowns and 2 eqns... So my question is how do you pose/solve a non-autonomous ode in mathematica? Thanks for any info in advance. Sean