add package problems

problems/function_fitting/xor.py

@@ -0,0 +1,13 @@
+import numpy as np
+
+from . import FunctionFittingProblem
+
+
+class Xor(FunctionFittingProblem):
+    def __init__(self):
+        self.num_inputs = 2
+        self.num_outputs = 1
+        self.batch = 4
+        self.inputs = np.array([[0, 0], [0, 1], [1, 0], [1, 1]], dtype=np.float32)
+        self.target = np.array([[0], [1], [1], [0]], dtype=np.float32)
+        super().__init__(self.num_inputs, self.num_outputs, self.batch, self.inputs, self.target)