Boundary cond. at Infinity
- To: mathgroup@smc.vnet.net
- Subject: [mg12097] Boundary cond. at Infinity
- From: Edward Goldobin <gold@dresden.isi.kfa-juelich.de>
- Date: Sat, 25 Apr 1998 01:30:29 -0400
- Organization: Research Center Juelich GmbH
I neet to solve diff. equation:
DSolve[
{
y''[x]-a^2 y[x]==Sinh[x]/Cosh[x]^2,
y[0]==0, y[Infinity]==0
},y[x],x
]
Math 3.0 complains about boundary condition at "Infinity". Well, I then
solve it with boundary cond. at zero only :
DSolve[
{
y''[x]-a^2 y[x]==Sinh[x]/Cosh[x]^2,
y[0]==0
},y[x],x
]
And Math.3.0 give me an answer in terms of PolyGamma's and
Hypergeometric2F1's with one constant C[2] which I want to find by
myself. To find it I need to know the behavior of e.g.
Hypergeometric2F1[(1 + a)/2, 1, 1 + (1 + a)/2, -E^(2*x)] at infinity.
How can I ask Mathematica to show me the behavior of arbitrary function
at infinity? I expect to get something like x*Exp[-2*x] i.e. Taylor is
of no use in this case since the behavior is exponential with unknown
power.
Your help will be appeciated very much. Send a copy of reply by email as
well. Thanx