Re: integrate problem
- To: mathgroup at smc.vnet.net
- Subject: [mg98851] Re: integrate problem
- From: "Sjoerd C. de Vries" <sjoerd.c.devries at gmail.com>
- Date: Mon, 20 Apr 2009 19:07:49 -0400 (EDT)
- References: <gshft4$c0o$1@smc.vnet.net>
Sean, 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 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. > > Sean