DEP: Deprecate `numpy.dual`.

Add a deprecation warning in the `numpy.dual` module, and
remove the use of `numpy.dual` from the few places where it
is used in the numpy code.

1 files changed, 8 insertions, 0 deletions

diff --git a/numpy/dual.py b/numpy/dual.py
index 92afec52d..9200a054e 100644
--- a/numpy/dual.py
+++ b/numpy/dual.py
@@ -10,6 +10,14 @@ NumPy.
 .. _Scipy : https://www.scipy.org
 
 """
+import warnings
+
+
+warnings.warn('The module numpy.dual is deprecated.  Instead of using dual, '
+              'use the functions directly from numpy or scipy.',
+              category=DeprecationWarning,
+              stacklevel=2)
+
 # This module should be used for functions both in numpy and scipy if
 #  you want to use the numpy version if available but the scipy version
 #  otherwise.