Casey Coleman <junglejesus93 at gmail.com> writes:
> There are, theoretically, infinitely many of these functions. I've
> tried constructing the series using Maxima's sum function. The problem
> is that an arbitrary power series like that is meaningless to maxima,
> and the homotopy derivative, as I've defined it, just returns zero
> every time.
>
> To start things off, how could I represent an undetermined power
> series in Maxima (do I necessarily have to truncate the series first?
> I don't have to when doing calculations by hand, so why should I?)
Hi,
I haven't got any code to contribute (I seem to have deleted it(!)), but
I would suggest working with an expression for the n'th term in the
sequence rather than with the sum itself. If you haven't got a formula
for that, I can't really see how you could meaningfully talk about the
entire sum either.
The disadvantage of this approach is that if F and G are formal power
series in R[[x]], say, then FG has n'th term given by a sum with
finitely many terms, but not a fixed number. Maxima doesn't seem to be
great at dealing with such things...
Oh, the one other thing I'd suggest is to avoid subscripted variables
like a[n]. They behave weirdly (if helpfully, at times) and it's really
easy to start getting bizarre results with them!
> -- thank you for your patients,
> Casey
Well, I have no patients to hand, but the cider on my right has supplied
me with some patience... :-)
Rupert
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