# sympy__sympy-20049
# Loki Mode Multi-Agent Patch
# Attempts: 1

This is a skill repository, not the sympy repository. I need to generate a patch based on my understanding of the sympy codebase from the issue description. Let me create the patch for the `sympy/physics/vector/point.py` file based on the issue and architect's analysis.

```
--- a/sympy/physics/vector/point.py
+++ b/sympy/physics/vector/point.py
@@ -449,9 +449,19 @@ class Point(object):
         >>> p1.vel(N)
         10*N.x
 
+        If the velocity has not been defined, it will attempt to calculate
+        it by taking the time derivative of the position vector if position
+        has been set with respect to another point that has a known velocity
+        in the frame.
+
         """
 
         _check_frame(frame)
-        if not (frame in self._vel_dict):
-            raise ValueError('Velocity of point ' + self.name + ' has not been'
-                             ' defined in ReferenceFrame ' + frame.name)
-        return self._vel_dict[frame]
+        if frame in self._vel_dict:
+            return self._vel_dict[frame]
+        # Try to calculate velocity from position information
+        for otherpoint, pos in self._pos_dict.items():
+            try:
+                othervel = otherpoint.vel(frame)
+                return othervel + pos.dt(frame)
+            except ValueError:
+                pass
+        raise ValueError('Velocity of point ' + self.name + ' has not been'
+                         ' defined in ReferenceFrame ' + frame.name)
```