# bug in minimal polynomials of finite fields

In a compiled version of 4.7 (64 bit, Debian Sid), I get:

```
----------------------------------------------------------------------
| Sage Version 4.7, Release Date: 2011-05-23 |
| Type notebook() for the GUI, and license() for information. |
----------------------------------------------------------------------
sage: F.<a>=GF(2^64)
sage: a.minpoly()
_3 = x^64 + x^33 + x^30 + x^26 + x^25 + x^24 + x^23 + x^22 + x^21 + x^20 + x^18 + x^13 + x^12 + x^11 + x^10 + x^7 + x^5 + x^4 + x^2 + x + 1
sage: K.<b>=GF(2^128)
sage: b.minpoly()
_5 = x^128 + x^7 + x^2 + x + 1
sage: a.minpoly()
_6 = x^128 + x^7 + x^2 + x + 1
```

Is this a bug or am I doing something stupid?

Thanks,

Luis

This bug is no longer observed in Sage 6.3 (and maybe before). A similar bug was observed, and fixed, in ticket #17094, see http://trac.sagemath.org/ticket/17094, and the fix made its way into Sage 6.4.beta5.