Igor Schein on Thu, 10 Jan 2002 16:24:05 -0500


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Re: Mordell Weil generator for y^2=x^3+7823 

Hi,

On Thu, Jan 10, 2002 at 04:05:07PM -0500, Michael Stoll wrote:
> Dear NMBRTHRYsts,
> 
> may I proudly present the generator of the Mordell-Weil group of
>   y^2 = x^3 + 7823 :
> 
> x = 2263582143321421502100209233517777/11981673410095561^2
> y = -186398152584623305624837551485596770028144776655756/11981673410095561^3
> 
> This point has canonical height 77.617773768638... as expected.

? x=2263582143321421502100209233517777/11981673410095561^2;
? y = -186398152584623305624837551485596770028144776655756/11981673410095561^3;
? ellheight(ellinit([0,0,0,0,7823]),[x,y])
38.80888688431904198640563870
? %*2
77.61777376863808397281127740

Where's the factor of 2 coming from?

Thanks

Igor