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Re: integrate problem

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  • Subject: [mg98851] Re: integrate problem
  • From: "Sjoerd C. de Vries" <sjoerd.c.devries at>
  • Date: Mon, 20 Apr 2009 19:07:49 -0400 (EDT)
  • References: <gshft4$c0o$>


What you are really asking is: how can I integrate an unknown function
of t?

The short answer is: you can't.

If you are going to integrate something, the least prerequisite is
that you know what this something is.

Just try s[t] = t and s[t]=Sin[t] to see what an enormous difference
this makes for the answer. It is clear that a general answer in terms
of s[t] would not be very possible or useful.

Cheers -- Sjoerd

On Apr 20, 11:39 am, sean_inc... at wrote:
> I'm having some issues understanding this...  Following works as
> expected.
> s is the variable in time.  a is a parameter.
> Integrate[1/(s + a), s]
> gives Log[a + s]
> But the following gives the integral itself.
> Integrate[1/(s[t] + a), t]
> If the function that needs to be integrated w.r.t time is 1/(s[t] +
> a), how do I accomplish that?  It seems like if integrate it wrt to s
> [t] it will work.
> Integrate[1/(s[t] + a), s[t]]
> But does that sound about right?
> Any thoughts appreciated.
> Sean

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