Fix tensor.add to diff. matrices properly

pygrad/nn.py

@@ -48,7 +48,7 @@ def single_pass():
 # Small test to see if autograd works.
 def test():
   # Input tensors.
-  x, y, z = tensor.Tensor(-2), tensor.Tensor(5), tensor.Tensor(-4)
+  x, y, z = tensor.Tensor(np.array([[1, 2, 3]])), tensor.Tensor(np.array([[2, 3, 4]])), tensor.Tensor(np.array([[1], [2], [3]]))
   
   # Forward pass.
   q = x.add(y)

pygrad/tensor.py

@@ -27,7 +27,7 @@ class Tensor:
     tensor._save(self, other)
 
     def back(upstream):
-      return np.dot(np.ones_like(self.value), upstream), np.dot(np.ones_like(self.value), upstream)
+      return np.dot(np.ones_like(self.value).T, upstream), np.dot(np.ones_like(self.value).T, upstream)
 
     tensor._back = back
     return tensor