Resolution of the Final ODE
We use the
gfun
package to solve for the solution
which corresponds to the integral to be computed. Due to its integral representation, this function is analytic at 0, hence admits a Taylor expansion at 0. We proceed to compute a closed form for
by summation of this expansion. To this end, we determine a recurrence equation on the coefficients of the Taylor expansion using
gfun[diffeqtorec]
:
>
Maple readily solves this recurrence:
> rsol:=rsolve(ore,u(n));
After rearranging the terms in the sum, it is obvious that
is non-zero for even
only.
> collect(map(normal,rsol,expanded),u,factor);
We perform the corresponding change of variable,
,
> subs({n=2*p,(-1)^n=1,RootOf(_Z^2+1)^n=(-1)^p},");
so that Maple can sum the Taylor series:
> sum("*a^(2*p),p=0..infinity);
> h:=collect(value(expand(")),u);
It only remains to evaluate
and
. We first compute
and find it is 0 by inversion of limits. Let
>
be the integrand. We have:
>
In the same way, each coefficient of the Taylor series for the integral is obtained by inversion of limits. In particular,
, but
Maple
is not capable of integrating:
> kappa=int(coeff(series(normal(diff(f,a,a)),a=0),a,0)/2,x=0..infinity);
(This integral for
cannot be computed by a call to
int
using the Release 4, but the next release will probably be able to integrate it.)
We obtain the following form for
:
> -combine(normal(-subs({u(0)=0,u(2)=kappa},h)),ln,symbolic);
It only remains to be proved that
. We do not do it, since computing this last integral which is a constant lies outside the scope of the theory of holonomy. With this example, we have reduced the problem of evaluating a parametrized integral to the evaluation of a non-parametrized integral. In case there were no closed form for
, we could at least perform a simple numerical evaluation and return a result in terms of this numerical value and the series above for
.