Add williamson type matrices of order 7

sagemath · Dec 7, 2022 · 129351f · 129351f
1 parent 8ba531e
commit 129351f
Showing 1 changed file with 4 additions and 0 deletions.
diff --git a/src/sage/combinat/matrices/hadamard_matrix.py b/src/sage/combinat/matrices/hadamard_matrix.py
@@ -333,6 +333,10 @@ def williamson_type_quadruples_smallcases(n, existence=False):
     """
     db = {
         1: ([1], [1], [1], [1]),
+        7: ([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],