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Remove unnecessary forcing to univariate #38151

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Merged
merged 6 commits into from
Jul 24, 2024
Merged

Remove unnecessary forcing to univariate #38151

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34a5f92
Fixing issue 38012
Jun 4, 2024
9d5a23a
Added comment saying purpose of change and reformated polynomial
Jun 4, 2024
7f64cf8
Update src/sage/dynamics/arithmetic_dynamics/projective_ds.py
Nathabolin Jun 6, 2024
8c97c99
Update src/sage/dynamics/arithmetic_dynamics/projective_ds.py
Nathabolin Jun 6, 2024
8a233f4
Merge branch 'develop' into 38012
Nathabolin Jun 7, 2024
6ad33ef
Merge branch 'develop' into 38012
Nathabolin Jul 2, 2024
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11 changes: 10 additions & 1 deletion src/sage/dynamics/arithmetic_dynamics/projective_ds.py
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Original file line number Diff line number Diff line change
Expand Up @@ -8437,6 +8437,14 @@ def normal_form(self, return_conjugation=False):
To: Finite Field in z2 of size 3^2
Defn: 1 |--> 1

Fixes :issue:`38012` by not forcing univariate polynomial to be univariate::

sage: R.<z> = PolynomialRing(QQ)
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The comment says an implementation detail that is not understandable by a user. The usual way to introduce a test (example) for a fix is

TEST:

Check that :issue:`38012` is fixed::

    sage: R.<z> = PolynomialRing(QQ)

sage: f = DynamicalSystem_affine(z^2 + z + 1).homogenize(1)
sage: f.normal_form()
Dynamical System of Projective Space of dimension 1 over Rational Field
Defn: Defined on coordinates by sending (x0 : x1) to
(x0^2 + 5/4*x1^2 : x1^2)
"""
# defines the field of fixed points
if self.codomain().dimension_relative() != 1:
Expand Down Expand Up @@ -8465,7 +8473,8 @@ def normal_form(self, return_conjugation=False):
#we find one and not go all the way to the splitting field
i = 0
if G.degree() != 0:
G = G.polynomial(G.variable(0))
if is_MPolynomialRing(G.parent()):
G = G.polynomial(G.variable(0))
else:
#no other fixed points
raise NotImplementedError("map is not a polynomial")
Expand Down