[GitHub] jermainewang commented on issue #8673: Autograd variable scope confusion

[GitBox <gi...@apache.org>]

jermainewang commented on issue #8673: Autograd variable scope confusion
URL: https://github.com/apache/incubator-mxnet/issues/8673#issuecomment-345037256
 
 
   Update:
   
   I further simplify the program a little bit to demo one of the weird behaviors:
   ```python
   def test1():
       a = nd.ones((2, 3), ctx=ctx)  # a is 1
       a_grad = nd.zeros((2, 3), ctx=ctx)
       ag.mark_variables(a, a_grad, 'write')
       with ag.record():
           b = a * 2
           #b.attach_grad()
           t = b * 3
           t.backward()
           PP(a.grad)
           PP(b.grad)
   ```
   
   In this example, `a.grad` should be 6, `b.grad` should be 3. However, if I uncomment  the line `b.attach_grad()`. `a.grad` becomes zero.

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