Re: DSolve Problem PDT)
- To: mathgroup at smc.vnet.net
- Subject: [mg16286] Re: DSolve Problem PDT)
- From: "Kevin J. McCann" <kevinmccann at Home.com>
- Date: Sun, 7 Mar 1999 01:05:27 -0500
- Organization: @Home Network
- References: <7bnph7$d1j@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Plug your initial value and t=0 into the differential equation and you
will see why. Your general problem is, in effect, taking a limit.
Kevin
Horst Finsterbusch wrote in message <7bnph7$d1j at smc.vnet.net>...
>Hello,
>
>Maybe you can help me: I do not understand, why a an
>empty list is in Out[3].
>
>Thanks Horst
>
>In[1]:= DSolve[{x'[t]==x[t]*(1-x[t]),x[a]==b},x[t],t]
>Out[1]= {{x[t] -> b*E^t / (E^a - b*E^a + b*E^t)}}
>In[2]:= % /. {a->0,b->1}
>Out[2]= {{x[t]->1}}
>
>In[3]:= DSolve[{x'[t]==x[t]*(1-x[t]),x[0]==1},x[t],t]
>Out[3]= {}
>