Revision history [back]

You might have misread the description that you copy paste. The arguments of K.hom must be the list of the images of the generators. In your case, there is one generator for K (which is gen1). Even L is an optional argument.

sage: K.hom([gen2])
Relative number field morphism:
  From: Number Field in gen1 with defining polynomial X^3 - zeta3 over its base field
  To:   Number Field in gen2 with defining polynomial X^3 + zeta3 + 1 over its base field
  Defn: gen1 |--> gen2
        zeta3 |--> -zeta3 - 1