Rafael Guglielmetti on Thu, 02 Mar 2017 10:05:18 +0100


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Re: Mathematica "Reduce" function


Dear all,
I step (maybe too late) in the discussion with a small question: If k is big, would it be interesting to parallelize the first (i.e. external) loop?

Best,

Rafael

On 03/02/2017 10:00 AM, Pedro Fortuny Ayuso wrote:
Thanks to all.

My specific problem is trying to solve equations like

6x^2 + 12y^2 +20z^2 = 0

over Z/(2^k)Z. That is, finding the points of that surface
over that ring.

Bill's reply of counting

length([[x,y,z]|x<-[0..2^k-1];y<-[0..2^k-1];z<-[0..2^k-1],6*x^2+12*y^2+20*z^2==0])

is the fastest but it ***looks like*** a lot slower than
Mathematica (but please notice I am working on a system
with pari/gp and my colleague on a different one with Mathematica,
so that it may have nothing to do with pari/Mathematica).

I know nothing about number theory, I just can guess what
'solving on the p-adics and then lifting' might mean but
am not quite ready to implement it.

Thanks again,


Pedro.