Re: Problems integrating InterpolatingFunction
- To: mathgroup at smc.vnet.net
- Subject: [mg116056] Re: Problems integrating InterpolatingFunction
- From: Roland Franzius <roland.franzius at uos.de>
- Date: Mon, 31 Jan 2011 03:23:31 -0500 (EST)
- References: <ii2c82$ra6$1@smc.vnet.net>
Am 30.01.2011 01:43, schrieb Sergio Miguel Terrazas Porras:
> Hello group,
>
> I use NDSolve for a nonlinear differential equation, and I get an InterpolatingFunction, as expected.
>
> I can plot it, evaluate it, etc.
>
> The problem I have is that now I need to integrate 1/(the square of the InterpolatingFunction), and I get nothing but the input back.
>
> Any ideas?
>
> Thanks in advance.
>
> Sergio Terrazas
>
Yoy can integrate InterpolatingFunction explitely using Derivative of
negative order
eg the critical soltion to the equations of motion of an anharmonic pendulum
X[t_] = x[t] /.
NDSolve[{x''[t] == -x[t]^3 + x[t], x'[0] == 0, x[0] == 1.42},
x[t], {t, 0, 100}] // First
Y[t_]=Derivative[-1][Y][t]
--
Roland Franzius