Hi,

I was trying this code:

sage: q = 3
sage: F.<a> = FiniteField(q)
sage: P.<T> = PolynomialRing(F)
sage: R.<z> = PowerSeriesRing(Q, default_prec = 50)
sage: load 'jc.sage'
sage: u = U(1)
sage: u
1 + 2*z^4 + (T^3 + 2*T)*z^6
sage: 1/u
1 + z^4 + (2*T^3 + T)*z^6 + z^8 + (T^3 + 2*T)*z^10 + (T^6 + T^4 + T^2
+ 1)*z^12 + z^16 + (2*T^9 + T)*z^18 + O(z^20)
sage: 1/(1 + 2*z^4 + (T^3 + 2*T)*z^6)
1 + z^4 + (2*T^3 + T)*z^6 + z^8 + (T^3 + 2*T)*z^10 + (T^6 + T^4 + T^2
+ 1)*z^12 + z^16 + (2*T^9 + T)*z^18 + z^20 + (2*T^9 + 2*T^3 + 2*T)
*z^22 + (T^12 + 2*T^10 + 2*T^4 + T^2 + 1)*z^24 + (2*T^9 + T^3)*z^26 +
(2*T^12 + T^10 + T^6 + 2*T^4 + 1)*z^28 + (2*T^15 + 2*T^13 + 2*T^11 +
2*T^9 + T^7 + T^5 + T^3 + T)*z^30 + z^32 + (T^9 + 2*T)*z^34 + (T^18 +
T^10 + T^2 + 1)*z^36 + (T^9 + 2*T^3)*z^38 + (T^18 + 2*T^12 + 2*T^10 +
T^4 + 1)*z^40 + (2*T^21 + T^19 + 2*T^13 + T^11 + T^9 + 2*T^5 + 2*T^3 +
T)*z^42 + (T^18 + T^12 + T^6 + 1)*z^44 + (T^21 + 2*T^19 + T^15 +
2*T^13 + T^9 + 2*T^7 + T^3 + 2*T)*z^46 + (T^24 + T^22 + T^20 + T^18 +
T^16 + T^14 + T^12 + T^10 + T^8 + T^6 + T^4 + T^2 + 1)*z^48 + O(z^50)

and found out that I could not keep a handle on the precision unless I
do it manually. The only explanation I have is that u is a Laurent
Series due to the fact that in the jc.sage I have to divide somewhere
by z and not a Power Series. Is this the explanation for losing the
precision? If so can I type cast it somehow back to R?

If not is this a bug?

Thanks in advance for viewing this. I can post the jc.sage file as
well, but it is a page or two.

~Alex


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