Re: changevar

[Karim BELABAS <Karim.Belabas@math.u-psud.fr>]

[I wrote:]
>> The changevar function is very hard to use reliably due to these phenomenons
>> unless you start the session by defining first the needed variables in the
>> correct order.
[Ilya answered:]
> Then why not change changevar so that it takes a transposition:
> 
>   changevars([x,y],[y,z],[z,x])

It's on the (new) TODO list (to be included in 2.0.16 (to be released
today (hopefully (!))))

GP DESIGN.
==========
[...]
2) changevar with explicit (incomplete) permutation. E.g 
changevar(p, [x,y,z], [a,b,c]) for x -> a, y -> b, z -> c
add a flag to perform it in succession or in parallel (e.g if a involves y)
[...]

Karim.
__
Karim Belabas                    email: Karim.Belabas@math.u-psud.fr
Dep. de Mathematiques, Bat. 425
Universite Paris-Sud             Tel: (00 33) 1 69 15 57 48
F-91405 Orsay (France)           Fax: (00 33) 1 69 15 60 19
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PARI/GP Home Page: http://hasse.mathematik.tu-muenchen.de/ntsw/pari/