       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)

```Use exact numbers

Off[Solve::ifun]

soln = DSolve[{y'[x] == 2/100*y[x] - y[x]^2, y == a}, y[x], x][]

{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]

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==a},y[x],x]

and get

During evaluation of In:= 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:= 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:= DSolve::bvnul: For some branches of the general solution, the given boundary conditions lead to an empty solution. >>

```

• Prev by Date: Re: Typesetting bug
• Next by Date: Re: Re: Scalar plot in 3D
• Previous by thread: Re: Problem with DSolve
• Next by thread: Re: Problem with DSolve