`sffctr'
--------

sffctr(POLY)
     :: Irreducible factorization over a small finite field.

RETURN
     list

POLY
     polynomial over a finite field

   * Factorize POLY into irreducible factors over a small finite field
     currently set.

   * The result is a list [[F1,M1],[F2,M2],...], where FI is a monic
     irreducible factor and MI is its multiplicity.

     [0] setmod_ff(2,10);
     [2,x^10+x^3+1,x]
     [1] sffctr((z*y^3+z*y)*x^3+(y^5+y^3+z*y^2+z)*x^2+z^11*y*x+z^10*y^3+z^11);
     [[@_0,1],[@_0*z*y*x+@_0*y^3+@_0*z,1],[(@_0*y+@_0)*x+@_0*z^5,2]]

References
     *Note `setmod_ff': setmod_ff, *Note `modfctr': modfctr

