DOC: document workaround for deprecation of dim-2 inputs to cross

rgommers · rgommers · commit 87d5f707528e · 2024-06-14T14:41:17.000+02:00
This addresses a part of gh-26620. The one-liner was verified and is likely to be used in a future `np.linalg.cross2d` function implementation, in gh-26640. [skip actions] [skip azp] [skip cirrus]
diff --git a/numpy/_core/numeric.py b/numpy/_core/numeric.py
@@ -1545,6 +1545,14 @@ def cross(a, b, axisa=-1, axisb=-1, axisc=-1, axis=None):
     c : ndarray
         Vector cross product(s).
 
+    Notes
+    -----
+    Dimension-2 input arrays were deprecated in 2.0.0. If you do need this
+    functionality, you can use::
+
+        def cross2d(x, y):
+            return x[..., 0] * y[..., 1] - x[..., 1] * y[..., 0]
+
     Raises
     ------
     ValueError
