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Re: NDSolve Question

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  • Subject: [mg86331] Re: NDSolve Question
  • From: "David Park" <djmpark at>
  • Date: Sat, 8 Mar 2008 05:44:47 -0500 (EST)

I found the answer, which is to use:

f[q_?NumberQ]:= ...

which prevents an initial evaluation.

David Park
djmpark at

"David Park" <djmpark at> wrote in message news:...
> Suppose I have a system like the following:
> f[q_]= some function with side affects
> NDSolve[{x'[t]==f[x[t]], x[0]==0},{x},{t, 0, 1}]
> My problem is that f[x[t]] seems to be evaluated before NDSolve starts 
> solving the equations and hence the routines always use the initially 
> evaluated form. I would like to have f[x[t]] to not be initially 
> evaluated. Is that possible with NDSolve? Is there any particular Method 
> or Option that can control the initial evaluation?
> -- 
> David Park
> djmpark at

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