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

[Richard B. Kreckel]

On 5/16/23 09:42, Vitaly Magerya wrote:
>> 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.

I guess some new code would have to be written to support this use case.

   -richy.