I extracted my data from csv file, and define like below:
x_train_tensor = Variable(torch.FloatTensor(x_train.values))
x_test_tensor = Variable(torch.FloatTensor(x_test.values))
y_train_tensor = Variable(torch.Tensor(y_train.values), requires_grad = True)
y_test_tensor = Variable(torch.Tensor(y_test.values), requires_grad = True)

is there any problem ?