ffgen

["Eric J. Van der Velden" <ericjvandervelden@gmail.com>]

I wanted to create a generator for F16. But ffinit gives a polynomial of order 5. So g is not a generator of F16*.

? g=ffgen([2,4],t)

%161 = t

? g.mod

%163 = t^4 + t^3 + t^2 + t + 1

? g^5

%167 = 1

So my first question is why ffinit comes up with a order 5 polynomial. 

Then I tried to take t^4+t+1, which has order 15: But then I am doing something wrong:

? P=x^4+x+1

%172 = x^4 + x + 1

? g=ffgen(P)

  ***   at top-level: g=ffgen(P)

  ***                   ^--------

  *** ffgen: incorrect type in ffgen (t_POL).

This is my second question.

Thank you!