Re: [Gretl-devel] convolve function into extra?
Am 20.03.2019 um 16:39 schrieb Allin Cottrell:
On Wed, 20 Mar 2019, Sven Schreiber wrote:
> Am 20.03.2019 um 02:05 schrieb Allin Cottrell:
>> On Tue, 19 Mar 2019, Allin Cottrell wrote:
>
>>>
>>> for p = the degree of the polynomial.
>>
>> Notation can be a bugger, and not wanting to be excessively pedantic
>> here, but is it a problem in the cheatsheet exposition that 'p' is
>> implicitly used to refer to both an array of coefficients and the length
>> of that array?
>
> In principle yes and it could be changed in one go. However, there I
> think the context is clear and one could say, the first p is in italics
> and the second one in typewriter font, so not exactly the same.
I've tried a modification of the cheat sheet text -- please check that I
haven't messed things up!
You write $r_k = \sum_{i=0}^k p_i q_{k-i}$ and I think that's basically
correct. Perhaps it's useful to clarify that within the sum it must also
hold $i \leq m$ and $k-i \leq n$ (equivalently $i \geq k-n$) because
otherwise the coefficients are zero; such that the sum index runs from
max(k-n, 0) to m, I believe.
cheers
sven