Re: DSolve Not Working
- To: mathgroup at smc.vnet.net
- Subject: [mg44935] Re: DSolve Not Working
- From: "Jens-Peer Kuska" <kuska at informatik.uni-leipzig-de>
- Date: Wed, 10 Dec 2003 04:01:40 -0500 (EST)
- Organization: Uni Leipzig
- References: <br4254$j1n$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Hi,
at first "ay" and "a y" are different things, the first is the symbol ay,
the second mean a*y
second my Mathematica 5.0 say
In[]:=DSolve[y''[x] == a y'[x] + y[x], y, x]
Out[]={{y -> Function[{x}, E^(((a - Sqrt[4 + a^2])*x)/2)*
C[1] + E^(((a + Sqrt[4 + a^2])*x)/2)*C[2]]}}
third the error message you report is inconsistent with your input.
The error message
> DSolve::dvnoarg: The function y appears with no arguments
comes typical from a forgotten argument, i.e.
DSolve[y'[x] == l*y, y[x], x]
instead of
DSolve[y'[x] == l y[x], y[x], x]
We *can* not help you if you don't provide your correct input!
Regards
Jens
"Will Oram" <spamguy at NOSPAM.foxchange.NOSPAM.com> schrieb im Newsbeitrag
news:br4254$j1n$1 at smc.vnet.net...
> I'm using Mathematica 5; DSolve[] never works. I am literally copying from
> its own documentation, and it still spits out failures. For example:
>
> In: DSolve[y''[x]==ay'[x]+y[x],y,x]
> DSolve::dvnoarg: The function y appears with no arguments
> Out: DSolve[y''[x]==(ay)/x+y[x],y,x]
>
> Wha?
>