Thanks for the reply. I've replied in context below.
On Mon, 2006-02-06 at 12:03 -0500, Stavros Macrakis wrote:
> Without looking at your problem closely, I see a couple of superficial
> problems:
> trigexpandplus:true,expand,all;
> trigexpandtimes:true,expand,all;
> trigexpand:true,expand,all;
>
> What are you trying to do here? These have the same effect as
>
> trigexpandplus:true;
> trigexpandtimes:true;
> trigexpand:true;
>
> The "expand,all" part has no effect.
I'd seen some of these in the info documentation examples; as you say
they have no effect (and AFAIK "true" is the default for some of these
anyhow). I've removed the extra stuff.
>
> g(x,t,x0):=sqrt(w/(2*%pi*sinh(w*t)))
> *exp(-w/(2*sinh(w*t))*((x**2
> +x0**2)*cosh(w*t)-2*x*x0));
>
> a:integrate(g(x1,t,x0)*x1**2*g(x0,b-t,x1),x1,minf,inf);
> b:integrate(g(x1,t,x0)*g(x0,b-t,x1),x1,minf,inf);
> c:trigsimp(a/b);
> ev(%,x0=0);
>
> You seem to be using "b" both as the name of a parameter and as an
> intermediate result in your calculation. I doubt that this is what
> you intend.
>
> In particular, it has the effect in the ev(...) expression of
> RE-EVALUATING b and substituting it back into the expression.
>
Oops. You're quite right. I have changed the b:integrate... as you
suggested and now I get:
trigsimp(%o11);
sinh((b - t) w) sinh(t w)
(%o13) ---------------------------------------------------------
w cosh((b - t) w) sinh(t w) + w sinh((b - t) w) cosh(t w)
The numerator is what I want; however, the denomenator will simplify to
w sinh (b w) if the cosh((b - t)w) and sinh((b -t)w) factors are
expanded.
David