Re: ricatti & set of ODE solution.
- To: mathgroup at smc.vnet.net
- Subject: [mg41692] Re: [mg41676] ricatti & set of ODE solution.
- From: Selwyn Hollis <selwynh at earthlink.net>
- Date: Sat, 31 May 2003 06:07:40 -0400 (EDT)
- Sender: owner-wri-mathgroup at wolfram.com
Hello Arda,
> here are the questions that i can't solve with mathematica.
> 1) i need to solve ricatti equation which ends at 2nd second, is it
> possible to solve with mathematica.
Not sure what you mean by "ends at 2nd second." What is typically
called a Riccati equation is one of the form x'[t] == a[t] + b[t]x[t] +
c[t]x[t]^2. Mathematica can solve some, but certainly not all,
equations of this type.
> 2) when solving set of ode i get error msgs.
> as i run these commands basicly to get solution:
>
> x[t_]={{x1[t]},{x2[t]}}
> at same where in the solution i get x'[t] in terms of x[t] and run
> sol=DSolve[{x'[t]==something,x[0]==somethingelse},x[t],t]
> and get error msg as x1[t] is not a function.
Is there a reason why you have x[t_]:={{x1[t]},{x2[t]}} instead of
x[t_]:={x1[t], x2[t]}? If so use Thread and Flatten:
sol = DSolve[Thread/@{x'[t] == something, x[0] == somethingelse},
Flatten[x[t]], t]
Otherwise just use Thread.
-----
Selwyn Hollis
http://www.math.armstrong.edu/faculty/hollis