Re: Finding Y coordinate

Bill Allombert on Tue, 05 Nov 2019 16:44:05 +0100

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Re: Finding Y coordinate

To: pari-users@pari.math.u-bordeaux.fr
Subject: Re: Finding Y coordinate
From: Bill Allombert <Bill.Allombert@math.u-bordeaux.fr>
Date: Tue, 5 Nov 2019 16:44:02 +0100
Delivery-date: Tue, 05 Nov 2019 16:44:05 +0100
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On Tue, Nov 05, 2019 at 03:19:29PM +0000, Pedro Patricio wrote:

> So you want a modular square root?
> 
> ? sqrt(Mod(2, 7))
> %1 = Mod(3, 7)
> 
> I would firstly compute the Legendre symbol in order to check the square
> root exists...

Indeed, GP has a function ellordinate() that does precisely that.

Cheers,
Bill

References:
- Elliptic Curve Creation and Scalar Multiplication
  - From: Tiago Mendes <tiagovazmendes7@gmail.com>
- Finding Y coordinate
  - From: Tiago Mendes <tiagovazmendes7@gmail.com>
- Re: Finding Y coordinate
  - From: Pedro Patricio <pedro@math.uminho.pt>

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