Add williamson type matrices of order 9

sagemath · Dec 7, 2022 · 8adf237 · 8adf237
1 parent 129351f
commit 8adf237
Showing 1 changed file with 5 additions and 1 deletion.
diff --git a/src/sage/combinat/matrices/hadamard_matrix.py b/src/sage/combinat/matrices/hadamard_matrix.py
@@ -337,6 +337,10 @@ def williamson_type_quadruples_smallcases(n, existence=False):
             [1, -1, 1, -1, -1, 1, -1],
             [1, 1, -1, -1, -1, -1, 1],
             [1, -1, -1, -1, -1, -1, -1]),
+        9: ([1, -1, -1, -1, 1, 1, -1, -1, -1],
+            [1, -1, -1, 1, -1, -1, 1, -1, -1],
+            [1, -1, 1, -1, -1, -1, -1, 1, -1],
+            [1, 1, -1, -1, -1, -1, -1, -1, 1]),
         29: ([1, 1, 1,-1,-1,-1, 1, 1,-1,-1, 1,-1, 1,-1,-1,-1,-1, 1,-1, 1,-1,-1, 1, 1,-1,-1,-1, 1, 1],
             [1,-1, 1,-1,-1,-1, 1, 1,-1,-1, 1,-1, 1, 1, 1, 1, 1, 1,-1, 1,-1,-1, 1, 1,-1,-1,-1, 1,-1],
             [1, 1, 1, 1,-1, 1, 1,-1, 1,-1,-1,-1, 1, 1, 1, 1, 1, 1,-1,-1,-1, 1,-1, 1, 1,-1, 1, 1, 1],
@@ -1361,7 +1365,7 @@ def hadamard_matrix(n,existence=False, check=True):
         False
         sage: matrix.hadamard(12,existence=True)
         True
-        sage: matrix.hadamard(476,existence=True)
+        sage: matrix.hadamard(668,existence=True)
         Unknown
         sage: matrix.hadamard(10)
         Traceback (most recent call last):