Data commit

Task/Determinant-and-permanent/11l/determinant-and-permanent.11l

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+F s_permutations(seq)
+   V items = [[Int]()]
+   L(j) seq
+      [[Int]] new_items
+      L(item) items
+         V i = L.index
+         I i % 2
+            new_items [+]= (0 .. item.len).map(i -> @item[0 .< i] [+] [@j] [+] @item[i ..])
+         E
+            new_items [+]= (item.len .< -1).step(-1).map(i -> @item[0 .< i] [+] [@j] [+] @item[i ..])
+      items = new_items
+
+   R enumerate(items).map((i, item) -> (item, I i % 2 {-1} E 1))
+
+F det(a)
+   V result = 0.0
+   L(sigma, _sign_) s_permutations(Array(0 .< a.len))
+      V x = Float(_sign_)
+      L(i) 0 .< a.len
+         x *= a[i][sigma[i]]
+      result += x
+   R result
+
+F perm(a)
+   V result = 0.0
+   L(sigma, _sign_) s_permutations(Array(0 .< a.len))
+      V x = 1.0
+      L(i) 0 .< a.len
+         x *= a[i][sigma[i]]
+      result += x
+   R result
+
+V a = [[1.0, 2.0],
+       [3.0, 4.0]]
+
+V b = [[Float( 1),  2,  3,  4],
+       [Float( 4),  5,  6,  7],
+       [Float( 7),  8,  9, 10],
+       [Float(10), 11, 12, 13]]
+
+V c = [[Float( 0),  1,  2,  3,  4],
+       [Float( 5),  6,  7,  8,  9],
+       [Float(10), 11, 12, 13, 14],
+       [Float(15), 16, 17, 18, 19],
+       [Float(20), 21, 22, 23, 24]]
+
+print(‘perm: ’perm(a)‘ det: ’det(a))
+print(‘perm: ’perm(b)‘ det: ’det(b))
+print(‘perm: ’perm(c)‘ det: ’det(c))