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Re: modular arithmetic (in finite field - part of elliptic curves)

  • To: mathgroup at smc.vnet.net
  • Subject: [mg84762] Re: modular arithmetic (in finite field - part of elliptic curves)
  • From: danl at wolfram.com
  • Date: Sun, 13 Jan 2008 05:44:39 -0500 (EST)
  • References: <fm9c0u$jbo$1@smc.vnet.net>

On Jan 11, 9:26 pm, Peppy <BrenOMah... at gmail.com> wrote:
> Part of my calculations give me
> 11/20 mod 23
>
> How can this be expressed as a whole number?
>
> I know 1/20 mod 23 = 15
> seeing that 15 * 20 mod 23 = 1 (inverse mod mult)
>
> Just wondering if it'd be 11 * 15 mod 23 which is 4?

Yes, that's right. Easiest way I know to find it in Mathematica uses
PolynomialMod.

In[1]:= PolynomialMod[11/20, 23]

Out[1]= 4

Daniel Lichtblau
Wolfram Research


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