Re: Solution of diff. equation i the form of list?
- To: mathgroup at smc.vnet.net
- Subject: [mg5526] Re: [mg5517] Solution of diff. equation i the form of list?
- From: "w.meeussen" <w.meeussen at solair4b.eunet.be>
- Date: Thu, 19 Dec 1996 01:02:28 -0500
- Sender: owner-wri-mathgroup at wolfram.com
At 19:26 14-12-96 -0500, you wrote:
>Hi!
>Can you write how to get the solution of differential
>equation in the form of list.
>I tried to achievie it in that way:
>
>DSolve[{z'[x]==-z[x],z[0]==1},z[x],x]
>data=Table[{x,z[x] /. %},{x,0.0,1.5,0.1}]
>
> and I got:
>
>{{z[x]->Exp[-x]}}
>{{{0.0,{1.0}},{0.1,{0.8}}, etc
> ^ ^ ^ ^
>
>How to get rid of above extra {}'s?
>If I use "data" list in "ListPlot[data]" function I got errors.
>
>If you know what to do please post or e-mail.
>
>Thanks in advance.
>
> Best regards
> Wojtek Wlazlo
> ufwlazlo at kinga.cyf-kr.edu.pl
>
>
>
hi Wojtek,
simple :
sol=DSolve[{z'[x]==-z[x],z[0]==1},z[x],x]
data=Table[{x,z[x] /.Flatten[sol]},{x,0.0,1.5,0.1}]
does what you need.
What happened? DSolve generally gives a list of lists-of-rules as answer.
Your case is simply a one-element list. The Wolframians wisely see it as the
users task to extract the single element from its enveloping 'packaging'.
Hence the Flatten[sol].
Don't despair, you'll get used to the style, and get to depend on its
consistency.
I wish you many more packaging to unwrap this christmas,
Wouter.
Dr. Wouter L. J. MEEUSSEN
w.meeussen at solair4b.eunet.be