Re: Hello

[Alasdair McAndrew <amca01@gmail.com>]

Your number p is composite (as has already been pointed out):

3^2 * 19 * 389 * 13829 * 575168189325963800313200253473 * 531174852026823987885634519017553

so of course not all non-zero residues will have an inverse.

-Alasdair

On Thu, Jul 12, 2012 at 12:33 AM, Karim Belabas <Karim.Belabas@math.u-bordeaux1.fr> wrote:

* Ahmad Kamal [2012-07-11 11:34]:

> Hi , i want to ask please about the command      x=random(p)    :
>
> what if i want to be sure that x has an inverse Mod p .

randominv(N) =
{ my(r);
  until(gcd(r,N) == 1, r = random(N));
  r
}

? vector(10,i,randominv(30))
%1 = [17, 1, 11, 17, 11, 29, 29, 17, 11, 7]

    K.B.
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Karim Belabas, IMB (UMR 5251)  Tel: (+33) (0)5 40 00 26 17
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