       Re: is this solvable?

• To: mathgroup at smc.vnet.net
• Subject: [mg56625] Re: is this solvable?
• From: ames kin <ames_kin at yahoo.com>
• Date: Sat, 30 Apr 2005 01:28:17 -0400 (EDT)
• Sender: owner-wri-mathgroup at wolfram.com

```Thanks to all those who have replied.

a'[t] + b'[t] == -p1 a[t] - p2 b[t]

is a result of operating on two odes that have 3 variables.

{
a'[t] == -p1 a[t] - p3 c[t]
b'[t] == p3 c[t] - p2 b[t]
}

adding the two equations allows me to get rid of p3 c[t] terms. ( Above system comes from a piece wise defined ODE system after a certain time point.)

but the problem was that I end up with the a'[t]+ b'[t]

dan's suggestion of setting b[t]-> b0 allows a particular form of solutions to be found using the normal DSolve syntax.

Don Taylor <dont at agora.rdrop.com> wrote:
In comp.soft-sys.math.mathematica you write:
>a'[t] + b'[t]== -p1 a[t] - p2 b[t]

>where {a== a0, b== b0}

>is this solvable in Mathematica? If so, how will I go about doing so?

>let's assume a== a0, and b==b0

>if symbolic solution isn't possible, then intial conditions of
>a== 1, and b==0.5 couild be used...(or any other numbers for that
>matter)