Bill Allombert on Sun, 13 Feb 2022 13:49:50 +0100


[Date Prev] [Date Next] [Thread Prev] [Thread Next] [Date Index] [Thread Index]

Re: elladd concern 

On Sun, Feb 13, 2022 at 01:31:47PM +0100, Pierre Charollois wrote:
> Hello,
> 
> I compute addition on an elliptic curve using two different ways,
> Sometimes I get the same output, sometimes not.
> 
> (13:21) *gp* > EE=ellinit([0,0,0,-1,0])
> 
> %449 = [0, 0, 0, -1, 0, 0, -2, 0, -1, 48, 0, 64, 1728, Vecsmall([1]),
> [Vecsmall([192, 1])], [0, 0, 0, 0, 0, 0, 0, 0]]
> 
> (13:21) *gp* > elladd(EE, ellztopoint(EE, I/3), ellztopoint(EE, 1/5))
> 
> %450 = [-2.505868825963744299759862918821279271135,
> 23.94289238927766278258847950281292062950]

This is not correct.  Which version of PARI/GP are you using ?
(The lastest version of PARI I found to have this bug is 2.7.5 from 2015).

Cheers,
Bill