Re: proper way of posing a non-autonomous ode in mathematica?
- To: mathgroup at smc.vnet.net
- Subject: [mg100433] Re: proper way of posing a non-autonomous ode in mathematica?
- From: dh <dh at metrohm.com>
- Date: Wed, 3 Jun 2009 05:28:37 -0400 (EDT)
- References: <h02vor$8fi$1@smc.vnet.net>
Hi Sean, see below, Daniel sean_incali at yahoo.com wrote: > 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] here k1 and k2 seem to be known > > 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... now, k1 and k2 seem to be unknown functions. Therefore, you need 2 more equations. > > So my question is how do you pose/solve a non-autonomous ode in > mathematica? > > Thanks for any info in advance. > > Sean > > > > >