Merge branch 'develop' into public/show_formulas_in_WeierstrassIsomorphism_documentation

Author: tobiasdiez

.github/PULL_REQUEST_TEMPLATE.md

@@ -1,6 +1,11 @@
+<!-- ^^^^^
+Please provide a concise, informative and self-explanatory title.
+Don't put issue numbers in there, do this in the PR body below.
+For example, instead of "Fixes #1234" use "Introduce new method to calculate 1+1"
+-->
 ### 📚 Description
 
-<!-- Describe your changes in detail -->
+<!-- Describe your changes here in detail -->
 <!-- Why is this change required? What problem does it solve? -->
 <!-- If it resolves an open issue, please link to the issue here. For example "Closes #1337" -->
 
@@ -10,6 +15,7 @@
 <!-- If your change requires a documentation PR, please link it appropriately -->
 <!-- If you're unsure about any of these, don't hesitate to ask. We're here to help! -->
 
+- [ ] I have made sure that the title is self-explanatory and the description concisely explains the PR.
 - [ ] I have linked an issue or discussion.
 - [ ] I have created tests covering the changes.
 - [ ] I have updated the documentation accordingly.

src/sage/schemes/elliptic_curves/ell_point.py

@@ -254,22 +254,19 @@ def __init__(self, curve, v, check=True):
             (1 : -2 : 1)
         """
         point_homset = curve.point_homset()
+        R = point_homset.value_ring()
         if is_SchemeMorphism(v) or isinstance(v, EllipticCurvePoint_field):
             v = list(v)
         elif v == 0:
-            # some of the code assumes that E(0) has integral entries
-            # regardless of the base ring...
-            # R = self.base_ring()
-            # v = (R.zero(),R.one(),R.zero())
-            v = (0, 1, 0)
+            v = (R.zero(), R.one(), R.zero())
         if check:
             # mostly from SchemeMorphism_point_projective_field
             d = point_homset.codomain().ambient_space().ngens()
             if not isinstance(v, (list, tuple)):
                 raise TypeError("Argument v (= %s) must be a scheme point, list, or tuple." % str(v))
             if len(v) != d and len(v) != d-1:
                 raise TypeError("v (=%s) must have %s components" % (v, d))
-            v = Sequence(v, point_homset.value_ring())
+            v = Sequence(v, R)
             if len(v) == d-1:     # very common special case
                 v.append(v.universe()(1))