haojin2 commented on a change in pull request #14673: [BUGFIX] fix ELU function
will appear nan when calculating the gradient
URL: https://github.com/apache/incubator-mxnet/pull/14673#discussion_r274750867
##########
File path: python/mxnet/gluon/nn/activations.py
##########
@@ -158,7 +158,8 @@ def __init__(self, alpha=1.0, **kwargs):
self._alpha = alpha
def hybrid_forward(self, F, x):
- return F.where(x > 0, x, self._alpha * (F.exp(x) - 1.0))
+ _x = F.where(x < 0, x, F.zeros_like(x))
+ return F.where(x > 0, x, self._alpha * (F.exp(_x) - 1.0))
Review comment:
Thanks for your contribution!
Actually we do have ELU implemented in the backend so you can call it
directly
Please use:
```Python
return F.LeakyReLU(x, act_type='elu', slope=self._alpha)
```
here instead and also you want to change:
https://github.com/apache/incubator-mxnet/blob/master/tests/python/unittest/test_gluon.py#L1183
to:
```Python
return mx.nd.expm1(x) if x <= 0.0 else x
```
so that the test would still pass after this change.
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