Re: Problem with DSolve
- To: mathgroup at smc.vnet.net
- Subject: [mg96467] Re: [mg96410] Problem with DSolve
- From: Bob Hanlon <hanlonr at cox.net>
- Date: Sat, 14 Feb 2009 03:09:16 -0500 (EST)
- Reply-to: hanlonr at cox.net
Use exact numbers
Off[Solve::ifun]
soln = DSolve[{y'[x] == 2/100*y[x] - y[x]^2, y[0] == a}, y[x], x][[1]]
{y(x)->(a E^(x/50))/(50 a E^(x/50)-50 a+1)}
soln /. x -> 0
{y(0)->a}
y'[x] == 2/100*y[x] - y[x]^2 /. NestList[D[#, x] &, soln[[1]], 1]
True
Bob Hanlon
---- Tony <aezajac at optonline.net> wrote:
=============
can anyone help what is wrong?
On version 7 I enter
DSolve[{y'[x]==.02*y[x]-y[x]^2,y[0]==a},y[x],x]
and get
During evaluation of In[58]:= Solve::ifun: Inverse functions are being used by Solve, so some solutions may not be found; use Reduce for complete solution information. >>
During evaluation of In[58]:= Solve::ifun: Inverse functions are being used by Solve, so some solutions may not be found; use Reduce for complete solution information. >>
During evaluation of In[58]:= DSolve::bvnul: For some branches of the general solution, the given boundary conditions lead to an empty solution. >>