GenericGraph.adjacency_matrix: Add doctest with immutable=True

sagemath · Feb 19, 2022 · 03343f7 · 03343f7
1 parent 01d5541
commit 03343f7
Showing 1 changed file with 12 additions and 0 deletions.
diff --git a/src/sage/graphs/generic_graph.py b/src/sage/graphs/generic_graph.py
@@ -1883,6 +1883,18 @@ def adjacency_matrix(self, sparse=None, vertices=None, *, base_ring=None, **kwds
             sage: type(_)
             <class 'sage.matrix.matrix_numpy_integer_dense.Matrix_numpy_integer_dense'>
 
+        As an immutable matrix::
+
+            sage: M = graphs.PathGraph(5).adjacency_matrix(sparse=False, immutable=True); M
+            [0 1 0 0 0]
+            [1 0 1 0 0]
+            [0 1 0 1 0]
+            [0 0 1 0 1]
+            [0 0 0 1 0]
+            sage: M[2, 2] = 1
+            Traceback (most recent call last):
+            ...
+            ValueError: matrix is immutable; please change a copy instead (i.e., use copy(M) to change a copy of M).
 
         TESTS::