new DSolve feature
- To: mathgroup at smc.vnet.net
- Subject: [mg46974] new DSolve feature
- From: Selwyn Hollis <sh2.7183 at misspelled.erthlink.net>
- Date: Thu, 18 Mar 2004 01:25:00 -0500 (EST)
- References: <c387p7$bij$1@smc.vnet.net> <200403170753.CAA16766@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
The following occurs in version 5.0.1 (Mac OS X).
This works as expected:
DSolve[x''[t] == -k x'[t] , x[t], t]
{{x[t] -> -(C[1]/(E^(k*t)*k)) + C[2]}}
So does this:
DSolve[{x''[t] == -k x'[t], x[0] == x0, x'[0] == 1}, x[t], t]
{{x[t] -> (-1 + E^(k*t) + E^(k*t)*k*x0)/(E^(k*t)*k)}}
However:
DSolve[{x''[t] == -k x'[t], x[0] == x0, x'[0] == v0}, x[t], t]
DSolve::bvnul: For some branches of the general solution,
the given boundary conditions lead to an empty solution.
{}
I wonder which "branches" of it are causing the difficulty. :^)
-----
Selwyn Hollis
http://www.math.armstrong.edu/faculty/hollis
(edit reply-to to reply)
- References:
- Re: Exact real solutions of cubic equations
- From: Paul Abbott <paul@physics.uwa.edu.au>
- Re: Exact real solutions of cubic equations