#!/usr/bin/env python
import torch
# x = torch.ones(2,2, requires_grad=True)
# print(x)

# y = x + 2

# print(y.grad_fn)

# z = y * y * 3
# out = z.mean()
# print(z, out)


a = torch.randn(2, 2)
a = ((a*3) / (a-1))

print(a.requires_grad)

a.requires_grad(True)

print(a.requires_grad)

b = (a*a).sum()