intpar.spad line 276 [edit on github]
This package implements factorPolynomial for Expression.
factor(p, [k1, ..., kn]) factors p into irreducible factors over field generated by its coefficients and k1, ..., kn.
factorPolynomial(p) factors p into irreducible factors over field generated by its coefficients.
poly_factor(p) should be local but conditional.