diff --git a/.gitignore b/.gitignore
index 0e8a9da..5f456dd 100644
--- a/.gitignore
+++ b/.gitignore
@@ -19,6 +19,7 @@ early-init.el
 example.py
 init.el
 latexmkrc
+nuggy.py
 org-store-link
 property-syntax-demonstration.org
 pyproject.toml
diff --git a/README.org b/README.org
index ca75963..3a73759 100644
--- a/README.org
+++ b/README.org
@@ -6147,12 +6147,15 @@ configures =code-cells=.
 :CUSTOM_ID: sec:debug-python
 :END:
 
-Listing [[lst:pdb-example]] shows how to start using PDB.  Links of interest are:
+Listing [[lst:pdb-example]] and [[lst:pdb-numpy]] show how to start using PDB.
+Links of interest are:
 - [[https://realpython.com/python-debugging-pdb/][Python Debugging with PDB]]
 - [[https://docs.python.org/3/library/pdb.html][The Python Debugger]]
 - [[yt:vfPtGsSJldg][Introduction to PDB (Python-2.7 YouTube video)]]
 - [[https://stackoverflow.com/questions/7668979/how-do-you-watch-a-variable-in-pdb][How do you watch a variable in PDB? (Python-2.7)]]
 - [[https://stackoverflow.com/questions/51349074/in-python-3-7-does-the-opcode-event-from-sys-settrace-give-any-information-ab][How to use the opcode event (Python-3.7, GAV: why does it fail)?]]
+- [[https://pypi.org/project/pdbpp/][PDB++]] looks incompatible with Python>3.10: see [[https://github.com/pdbpp/pdbpp/issues/516][Python-3.11 breaks PDBPP]].
+- [[https://python-scientific-lecture-notes.developpez.com/tutoriel/notes-cours/python-debugging-code/#L3-1][Debugging Python with IPDB under IPython or with PDB in a terminal]].
 
 #+caption[PDB example: =python -m pdb .emacs.d/buggy.py=]:
 #+caption: PDB example: =python -m pdb .emacs.d/buggy.py=.
@@ -6166,6 +6169,27 @@ if __name__ == "__main__":
     unsafe(1.0, 0.0)
 #+end_src
 
+#+caption[PDB NumPy example: =python -m pdb .emacs.d/nuggy.py=]:
+#+caption: PDB NumPy example: =python -m pdb .emacs.d/nuggy.py=.
+#+name: lst:pdb-numpy
+#+begin_src python -i -n :results silent
+def buggy():
+    from numpy import array, matrix
+    from numpy.linalg import inv
+
+    a = matrix(array([[1.0, 1.0], [1.0, 1.0]]))
+    breakpoint()
+    # Use "display", "p", or "pp" to inspect "a".
+    # A series of "s" does not raise the exception here, contrary to "c".
+    b = inv(a)
+    breakpoint()
+    return b
+
+if __name__ == "__main__":
+    b = buggy()
+    # The series of "s" says only here "Uncaught exception".
+#+end_src
+
 * [[https://github.com/emacs-tw/awesome-emacs#library][Libraries]]
 :PROPERTIES:
 :CUSTOM_ID: sec:libraries