def identity(self):
"""
The identity map of this homset.
.. NOTE::
Of course, this only exists for sets of endomorphisms.
EXAMPLES::
sage: H = Hom(QQ,QQ)
sage: H.identity()
Identity endomorphism of Rational Field
sage: H = Hom(ZZ,QQ)
sage: H.identity()
Traceback (most recent call last):
...
TypeError: Identity map only defined for endomorphisms. Try natural_map() instead.
sage: H.natural_map()
Ring Coercion morphism:
From: Integer Ring
To: Rational Field
"""
if self.is_endomorphism_set():
return morphism.IdentityMorphism(self)
else:
raise TypeError, "Identity map only defined for endomorphisms. Try natural_map() instead."
def identity(self):
if self.is_endomorphism_set():
return morphism.IdentityMorphism(self)
else:
raise TypeError, "Identity map only defined for endomorphisms. Try natural_map() instead."