Re: Member Functions

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

Follow-up to myself:
> > Is it possible to define new member functions with pari?, i would like to
> > create new structures (similar to elliptic functions or number fields) and
> > extract the information via the "dot" notation.
> 
> It's not possible interactively. You have to modify the source code. It will
> be quite easy if you're minimally profficient with C (or have access to
> somebody who is): just add the new "member" in gp_member_list (in
> language/anal.c) and write the corresponding (trivial) C function.
>
> [... quick C sample deleted ...]
> 
> An interface to GP scripting language would be easily implemented, so that
> new members could be defined at GP level and call a user function instead
> of a pre-compiled routine. The above definition might then look like:
> 
> check_ell_type(x)= if (type(x) != "t_VEC" || length(x) < 14, error("..."))
> 
> x.j= check_ell_type(x); ell[13]
> 
> I'll think about it. Don't expect it in 2.0.12, though...

I lied: this will be in 2.0.12. The syntax

  check_ell_type(x)= if (type(x) != "t_VEC" || length(x) < 14, error("..."))
  ell.j = check_ell_type(ell); ell[13] \\ better than the obvious typo above...

or equivalently

{
  ell.j = 
  if (...);
  ell[13]
}

is recognized right now in my private version ["x.z" statements are treated
as special instances of user functions ".z" with a single argument "x"].

Karim, packaging 2.0.12.
--
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
--
PARI/GP Home Page: http://pari.home.ml.org