Re: integrate problem

• To: mathgroup at smc.vnet.net
• Subject: [mg98849] Re: integrate problem
• From: Erik Max Francis <max at alcyone.com>
• Date: Mon, 20 Apr 2009 19:07:27 -0400 (EDT)
• References: <gshft4\$c0o\$1@smc.vnet.net>

```sean_incali at yahoo.com 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.

In your examples, is a constant, but s[t] is a function of t.  You
haven't specified what that function is, so Mathematica can't simplify
it beyond recognizing that you're asking for a symbolic integral.
Specify what s[t] is either inline in the Integrate function or
separately with a definition before trying to integrate 1/(s[t] + a).

--
Erik Max Francis && max at alcyone.com && http://www.alcyone.com/max/
San Jose, CA, USA && 37 18 N 121 57 W && AIM, Y!M, Skype erikmaxfrancis
Whom God has put asunder, why should man put together?
-- Ralph Waldo Emerson

```

• Prev by Date: Re: integrate problem
• Next by Date: Re: factor out a term to cancel in a fraction
• Previous by thread: Re: integrate problem
• Next by thread: NumberForm spaces and commas in v7.0.1