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