Adding modules to compute determinates of 2z2 and 3x3 arrays

determinate2x2.py

@@ -0,0 +1,8 @@
+from typing import List
+
+def det2x2(llist: List[List[int]])->int:
+    assert len(llist) == 2 and len(llist[0]) == 2, "Matrix is not 2x2"
+    z = list(zip(llist[0], llist[1][::-1]))
+    det = z[0][0]*z[0][1] - z[1][0]*z[1][1]
+    return det
+

determinate3x3.py

@@ -0,0 +1,37 @@
+from typing import List
+import determinate2x2
+import copy
+
+
+def neg_odd_vals(lst: List[int])-> List[int]:
+    return [-val if i % 2 == 1 else val for i, val in enumerate(lst)]
+
+def det3x3(M: List[List[int]])->int:
+    assert len(M) == 3 and len(M[0]) == 3, "Matrix is not 3x3"
+    # Matrix M with row 0 and col 0 removed
+    N = copy.deepcopy(M)
+    N[1].remove(N[1][0]) 
+    N[2].remove(N[2][0])
+    A = [N[1], N[2]]
+
+    #Matrix M with row 0 and col 1 removed
+    N = copy.deepcopy(M)
+    N[1].remove(N[1][1]) 
+    N[2].remove(N[2][1])
+    B = [N[1], N[2]]
+
+    #Matrix M with row 0 and col 2 removed
+    N = copy.deepcopy(M)
+    N[1].remove(N[1][2])
+    N[2].remove(N[2][2])    
+    C = [N[1], N[2]]
+ 
+    # List M[0] with every odd index value set to its negative
+    N0 = neg_odd_vals(N[0])
+    
+    # Sum of determinates A, B, C times their respective multipliers
+    det0 = N0[0]*determinate2x2.det2x2(A)
+    det1 = N0[1]*determinate2x2.det2x2(B)
+    det2 = N0[2]*determinate2x2.det2x2(C)
+    return det0 + det1 + det2
+