[GiNaC-list] Any way to get the leading order of a series expansion?

[Vitaly Magerya]

> Well, that's deliberate.
>
> If I have a series of, say, exp(x) at 0 and another one of cos(x) at 0
> and you ask GiNaC to compute them to order N, then you get two series
> ending with the same Order(x^N), which you can add, zip, and compare
> term-by-term. In contrast, asking for "the first N orders" would get you
> about twice as far for cos(x) as for exp(x).

I understand this use case, but ours is different. We have integrals
that need to be expanded to a given order; each integral has a
prefactor; we have our method of expanding integrals without
prefactors, but we need to know the orders in advance, so knowing
the leading order of the prefactor is an essential first step.

> This was done for computations in dimensional regularization where one
> wants to make sure to catch all terms up to some pre-known order.
>
> Maybe you could explain your use-case a bit more? Are you really
> interested in "the first N orders" or just "the leading order"?

Just the leading order is sufficient.