A-M baby

Task/Matrix-arithmetic/Python/matrix-arithmetic.py

@@ -0,0 +1,45 @@
+from itertools import permutations
+from operator import mul
+from math import fsum
+from spermutations import spermutations
+
+def prod(lst):
+    return reduce(mul, lst, 1)
+
+def perm(a):
+    n = len(a)
+    r = range(n)
+    s = permutations(r)
+    return fsum(prod(a[i][sigma[i]] for i in r) for sigma in s)
+
+def det(a):
+    n = len(a)
+    r = range(n)
+    s = spermutations(n)
+    return fsum(sign * prod(a[i][sigma[i]] for i in r)
+                for sigma, sign in s)
+
+if __name__ == '__main__':
+    from pprint import pprint as pp
+
+    for a in (
+            [
+             [1, 2],
+             [3, 4]],
+
+            [
+             [1, 2, 3, 4],
+             [4, 5, 6, 7],
+             [7, 8, 9, 10],
+             [10, 11, 12, 13]],
+
+            [
+             [ 0,  1,  2,  3,  4],
+             [ 5,  6,  7,  8,  9],
+             [10, 11, 12, 13, 14],
+             [15, 16, 17, 18, 19],
+             [20, 21, 22, 23, 24]],
+        ):
+        print('')
+        pp(a)
+        print('Perm: %s Det: %s' % (perm(a), det(a)))