Fixes sympy#7757

Author: akshayah3

sympy/geometry/line3d.py

@@ -707,9 +707,7 @@ def intersection(self, o):
             b = o.arbitrary_point(t2)
             c = solve([a.x - b.x, a.y - b.y], [t1, t2])
             d = solve([a.x - b.x, a.z - b.z], [t1, t2])
-            if len(c) == 1:
-                return []
-            if len(d) == 1:
+            if len(c) == 1 and len(d) == 1:
                 return []
             if c is {}:
                 e = a.subs(t1, d[t1])

sympy/geometry/plane.py

@@ -638,7 +638,7 @@ def intersection(self, o):
         from sympy.geometry.line import LinearEntity
         if isinstance(o, Point) or isinstance(o, Point3D):
             if o in self:
-                return o
+                return [o]
             else:
                 return []
         if isinstance(o, LinearEntity3D):
@@ -655,7 +655,7 @@ def intersection(self, o):
                 else:
                     a = a.subs(t, c[0])
                     if a in o:
-                        return a
+                        return [a]
                     else:
                         return []
         if isinstance(o, LinearEntity):
@@ -673,7 +673,7 @@ def intersection(self, o):
                     return [Point(c[x], c[y])]
         if isinstance(o, Plane):
             if o == self:
-                return self
+                return [self]
             if self.is_parallel(o):
                 return []
             else:

sympy/geometry/tests/test_geometry.py

@@ -564,6 +564,10 @@ def test_line3d():
     assert intersection(l1, p5) == []
     assert intersection(l1, l1.parallel_line(p1)) == [Line3D(Point3D(0, 0, 0), Point3D(1, 1, 1))]
 
+    p = Ray3D(Point3D(1, 0, 0), Point3D(-1, 0, 0))
+    q = Ray3D(Point3D(0, 1, 0), Point3D(0, -1, 0))
+    assert intersection(p, q) == [Point3D(0, 0, 0)]
+
     # Concurrency
     assert Line3D.is_concurrent(l1) is False
     assert Line3D.is_concurrent(l1, l2)
@@ -736,10 +740,10 @@ def test_plane():
     assert pl6.perpendicular_line(Point3D(6, 4, 2)) == \
                Line3D(Point3D(6, 4, 2), Point3D(8, 6, 4))
 
-    assert pl6.intersection(pl6) == pl6
-    assert pl4.intersection(pl4.p1) == pl4.p1
+    assert pl6.intersection(pl6) == [pl6]
+    assert pl4.intersection(pl4.p1) == [pl4.p1]
     assert pl3.intersection(pl6) == [Line3D(Point3D(8, 4, 0), Point3D(2, 4, 6))]
-    assert pl3.intersection(Line3D(Point3D(1,2,4), Point3D(4,4,2))) == Point3D(2, 8/3, 10/3)
+    assert pl3.intersection(Line3D(Point3D(1,2,4), Point3D(4,4,2))) == [Point3D(2, 8/3, 10/3)]
     assert pl3.intersection(Plane(Point3D(6, 0, 0), normal_vector=(2, -5, 3))) == \
                [Line3D(Point3D(-24, -12, 0), Point3D(-25, -13, -1))]