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