Can't run test.py

[gitUserGoodLeaner]

@liuhu-bigeye Can't run test script, the error output like this:
I0414 09:26:43.509974 98 seg_ctc_ent_log_fb.py:171] alphas.size():torch.Size([1, 20, 12])
I0414 09:26:43.510052 98 seg_ctc_ent_log_fb.py:172] alphas[:-1].size():torch.Size([0, 20, 12])
I0414 09:26:43.510107 98 seg_ctc_ent_log_fb.py:173] alphas_in.size():torch.Size([0, 69])
I0414 09:26:43.510155 98 seg_ctc_ent_log_fb.py:174] pred_blank_in.size():torch.Size([19, 69])
I0414 09:26:43.510199 98 seg_ctc_ent_log_fb.py:175] betas_in.size():torch.Size([19, 69])
I0414 09:26:43.515330 98 seg_ctc_ent_log_fb.py:171] alphas.size():torch.Size([1, 20, 12])
I0414 09:26:43.515409 98 seg_ctc_ent_log_fb.py:172] alphas[:-1].size():torch.Size([0, 20, 12])
I0414 09:26:43.515462 98 seg_ctc_ent_log_fb.py:173] alphas_in.size():torch.Size([0, 69])
I0414 09:26:43.515514 98 seg_ctc_ent_log_fb.py:174] pred_blank_in.size():torch.Size([20, 69])
I0414 09:26:43.515559 98 seg_ctc_ent_log_fb.py:175] betas_in.size():torch.Size([20, 69])
I0414 09:26:43.520695 98 seg_ctc_ent_log_fb.py:171] alphas.size():torch.Size([1, 20, 12])
I0414 09:26:43.520773 98 seg_ctc_ent_log_fb.py:172] alphas[:-1].size():torch.Size([0, 20, 12])
I0414 09:26:43.520830 98 seg_ctc_ent_log_fb.py:173] alphas_in.size():torch.Size([0, 69])
I0414 09:26:43.520878 98 seg_ctc_ent_log_fb.py:174] pred_blank_in.size():torch.Size([21, 69])
I0414 09:26:43.520923 98 seg_ctc_ent_log_fb.py:175] betas_in.size():torch.Size([21, 69])
I0414 09:26:43.526067 98 seg_ctc_ent_log_fb.py:171] alphas.size():torch.Size([1, 20, 12])
I0414 09:26:43.526146 98 seg_ctc_ent_log_fb.py:172] alphas[:-1].size():torch.Size([0, 20, 12])
I0414 09:26:43.526200 98 seg_ctc_ent_log_fb.py:173] alphas_in.size():torch.Size([0, 69])
I0414 09:26:43.526250 98 seg_ctc_ent_log_fb.py:174] pred_blank_in.size():torch.Size([22, 69])
I0414 09:26:43.526310 98 seg_ctc_ent_log_fb.py:175] betas_in.size():torch.Size([22, 69])
I0414 09:26:43.531480 98 seg_ctc_ent_log_fb.py:171] alphas.size():torch.Size([1, 20, 12])
I0414 09:26:43.531559 98 seg_ctc_ent_log_fb.py:172] alphas[:-1].size():torch.Size([0, 20, 12])
I0414 09:26:43.531629 98 seg_ctc_ent_log_fb.py:173] alphas_in.size():torch.Size([0, 69])
I0414 09:26:43.531694 98 seg_ctc_ent_log_fb.py:174] pred_blank_in.size():torch.Size([23, 69])
I0414 09:26:43.531757 98 seg_ctc_ent_log_fb.py:175] betas_in.size():torch.Size([23, 69])
I0414 09:26:43.536949 98 seg_ctc_ent_log_fb.py:171] alphas.size():torch.Size([1, 20, 12])
I0414 09:26:43.537029 98 seg_ctc_ent_log_fb.py:172] alphas[:-1].size():torch.Size([0, 20, 12])
I0414 09:26:43.537085 98 seg_ctc_ent_log_fb.py:173] alphas_in.size():torch.Size([0, 69])
I0414 09:26:43.537133 98 seg_ctc_ent_log_fb.py:174] pred_blank_in.size():torch.Size([24, 69])
I0414 09:26:43.537179 98 seg_ctc_ent_log_fb.py:175] betas_in.size():torch.Size([24, 69])
Traceback (most recent call last):
File "pytorch_ctc/seg_ctc_ent_log_fb.py", line 219, in
test_seg_ctc(use_mine=True)
File "pytorch_ctc/seg_ctc_ent_log_fb.py", line 90, in test_seg_ctc
cost.backward()
File "/usr/local/lib/python3.6/site-packages/torch/tensor.py", line 118, in backward
torch.autograd.backward(self, gradient, retain_graph, create_graph)
File "/usr/local/lib/python3.6/site-packages/torch/autograd/init.py", line 93, in backward
allow_unreachable=True) # allow_unreachable flag
RuntimeError: element 0 of tensors does not require grad and does not have a grad_fn