Re: stupid question
- To: mathgroup at smc.vnet.net
- Subject: [mg34103] Re: [mg34081] stupid question
- From: BobHanlon at aol.com
- Date: Sat, 4 May 2002 04:28:21 -0400 (EDT)
- Sender: owner-wri-mathgroup at wolfram.com
In a message dated 5/2/02 4:36:58 AM, heimantj at celera.com writes:
>I am a mathematica newbie. I have a first order equation that
>describes the amount of a compound at time t, it is a periodic system
>and the compound is either present or not (a step function):
>
>dA(t)/dt=S(t)-ln(2)/halflife*A(t)
>
>S(t) = S if T1<t<t2
>S(t) = 0 otherwise
>
>Does anybody have an idea how I would solve this using mathematica to
>obtain the formal solution. I would really appreciate any
>suggestions!! Thankyou!!
>
eqn =
(A'[t]== S*(UnitStep[t-t1]-UnitStep[t-t2])-Log[2]/halflife*A[t]);
soln = DSolve[eqn, A[t], t]//
Flatten//FullSimplify
with a boundary condition
soln = DSolve[{eqn,A[0]==0},
A[t], t]//Flatten//FullSimplify
Bob Hanlon
Chantilly, VA USA