Max Alekseyev on Sat, 13 Jul 2019 12:12:53 +0200


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components of t_PADIC


Hello,

The documentation for component(x,n) gives an example:

      ? x = 3 + O(3^5);
      ? component(x, 2)
      %2 = 81   \\ p^(p-adic accuracy)

This example does work as stated, however for p=2 the behavior is different:

? x = 4 + O(2^3)
%1 = 2^2 + O(2^3)
? component(x,2)
%2 = 2
? x.mod
%3 = 2

So, both component(x,2) and x.mod here give 2 instead of 8. Is this a bug?

Speaking along these lines, what would the easiest way to covert t_PADIC to t_INTMOD?
I was thinking about Mod(lift(x),x.mod), but because of the aforementioned behavior the safe way seems to be Mod(lift(x),x.p^padicprec(x,x.p)). Is there a more straightforward way?

Thanks,
Max

P.S. Just in case, I use GP/PARI CALCULATOR Version 2.12.1 (development 23999-918d8bb62) at the moment.