>
> Sorry for the silence. So, the GSoC coding period has started and I've
> finished the implementation of the newtonpolygon
> function [1]. Could you please review it?
Some remarks:
1) It make sense to pass argument of type LODO3 to newtonpolygon.
In fact, it makes sense to pass operator having Laurent series
coefficient. So convertion from LODO1 and change of coefficient
would be at upper level
2) There is a two argument version of order function:
order(c, n)
will give you min of order(c) and n. So no need to test if
c is 0 (in particular this avoids problems when c has infinite
number of zero coefficients).
3) You replace missing coefficients of the operator by 0. This
is OK if leading coefficient of the operator is has order 0
but may be wrong if operator has positive order. Using order
of leading coefficient instead of 0 would be OK, but probably
it is better just work only with coefficients that are present.
4) You use a lot indexing on lists. In general this is inefficient
and frequently means that array would be more appropriate.
In this case intead of indexing use interation over lists.
5) It makes sense to split newtonpolygon into smaller functions.
In particular extracting coordinates of points, computing convex
envelope and computing polys associated to slopes could be done
by separate functions.
6) I do not see why you have "failed" as part of the result?
Whithout it the result would be simpler.
7) AFAICS you use quadratic method for computing convex envelope.
There is simple linear method. Namely given points a1, ..., an
given in increasing order of x-coordinate we proceed as follows.
We keep a tentative list of points with slopes [[p1, s1], ..., [pk, sk]].
At the beginning we accept [a1, 0] to tentative list. Then we
handle a2, ..., an iteratively. In itertaion dealing with al we
compare slope between pk and al and sk. If sk is bigger or equal,
then we drop [pk, sk] from tentative lists. We keep dropping points
and stop when we find [pi, si] with slope between pi and al bigger
than si. Then we add al with the slope between pi and al to
tentative list.
> Here are some known issues so far:
>
> 1. lodo3.spad and task2.spad are unnecessary as the contents of
> lodo3.spad can be pushed into lodo.spad; however,
I will add lodo3.spad to lodo.spad
> I'm not so sure about
> contents of task2.spad. Any ideas on where the package should go and
> what it's name should be?
It is related to lodo3.spad, so it makes sense to put it in the
same file. Concerning names, I will probably call it
'LODOConvertions' and call the exported operation just 'convert'.
> 2. On compiling the function, I get the following:
> Warnings:
> [1] newtonpolygon: y has no value
> [2] newtonpolygon: x has no value
> Though this doesn't seem to cause issues related to the correctness of
> the answers, it'd still be good if I could make it go away.
This is supposed to mean that z and y are used uninitilized. But
in your case warning seems spurious.
--
Waldek Hebisch
[email protected]
--
You received this message because you are subscribed to the Google Groups
"FriCAS - computer algebra system" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
To post to this group, send email to [email protected].
Visit this group at http://groups.google.com/group/fricas-devel.
For more options, visit https://groups.google.com/d/optout.
