10.5.1 `setmod_ff'
------------------

setmod_ff([P|DEFPOLY2])
setmod_ff([DEFPOLYP,P])
setmod_ff([P,N])
     :: $BM-8BBN$N@_Dj(B, $B@_Dj$5$l$F$$$kM-8BBN$NK!(B, $BDj5AB?9`<0$NI=<((B

RETURN
     $B?t$^$?$OB?9`<0(B

P
     $BAG?t(B

DEFPOLY2
     GF(2) $B>e4{Ls$J(B 1 $BJQ?tB?9`<0(B

DEFPOLYP
     GF(P) $B>e4{Ls$J(B 1 $BJQ?tB?9`<0(B

N
     $B3HBg<!?t(B

   * $B0z?t$,@5@0?t(B P $B$N;~(B, GF(P) $B$r4pACBN$H$7$F@_Dj$9$k(B.

   * $B0z?t$,B?9`<0(B DEFPOLY2 $B$N;~(B, GF(2^deg(DEFPOLY2 mod 2)) =
     GF(2)[t]/(DEFPOLY2(t) mod 2) $B$r4pACBN$H$7$F@_Dj$9$k(B.

   * $B0z?t$,(B DEFPOLYP $B$H(B P $B$N;~(B, GF(P^DEG(DEFPOLYP))
     $B$r4pACBN$H$7$F@_Dj$9$k(B.

   * $B0z?t$,(B P $B$H(B N $B$N;~(B, GF(P^N) $B$r4pACBN$H$7$F@_Dj$9$k(B. P^N $B$O(B 2^29
     $BL$K~$G(B $B$J$1$l$P$J$i$J$$(B. $B$^$?(B, P $B$,(B 2^14 $B0J>e$N$H$-(B, N $B$O(B 1
     $B$G$J$1$l$P$J$i$J$$(B.

   * $BL50z?t$N;~(B, $B@_Dj$5$l$F$$$k4pACBN$,(B GF(P)$B$N>l9g(B P, GF(2^N)
     $B$N>l9gDj5AB?9`<0$rJV$9(B.  $B4pACBN$,(B `setmod_ff(DEFPOLY,P)'
     $B$GDj5A$5$l$?(B GF(P^N) $B$N>l9g(B, [DEFPOLY,P] $B$rJV$9(B.  $B4pACBN$,(B
     `setmod_ff(P,N)' $B$GDj5A$5$l$?(B GF(p^N) $B$N>l9g(B,
     [P,DEFPOLY,PRIM_ELEM] $B$rJV$9(B. $B$3$3$G(B, DEFPOLY $B$O(B, N
     $B<!3HBg$NDj5AB?9`<0(B, PRIM_ELEM $B$O(B, GF(P^N)$B$N(B
     $B>hK!72$N@8@.85$r0UL#$9$k(B.

   * GF(2^N) $B$NDj5AB?9`<0$O(B, GF(2) $B>e(B n $B<!4{Ls$J$i$J$s$G$bNI$$$,(B, $B8zN($K(B
     $B1F6A$9$k$?$a(B, `defpoly_mod2()' $B$G@8@.$9$k$N$,$h$$(B.

     [174] defpoly_mod2(100);
     x^100+x^15+1
     [175] setmod_ff(@@);
     x^100+x^15+1
     [176] setmod_ff();
     x^100+x^15+1
     [177] setmod_ff(x^4+x+1,547);
     [1*x^4+1*x+1,547]
     [178] setmod_ff(2,5);
     [2,x^5+x^2+1,x]

$B;2>H(B
     *Note `defpoly_mod2': defpoly_mod2.

