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Stabilized softmax use instead of unstable version

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AntreasAntoniou 2017-11-10 19:13:54 +00:00
parent e7fc62cd09
commit 6a0cdbea3a
1 changed files with 2 additions and 2 deletions
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mlp/errors.py
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@ -154,7 +154,7 @@ class CrossEntropySoftmaxError(object):
Returns: Returns:
Scalar error function value. Scalar error function value.
""" """
probs = np.exp(outputs) probs = np.exp(outputs - outputs.max(-1)[:, None])
probs /= probs.sum(-1)[:, None] probs /= probs.sum(-1)[:, None]
return -np.mean(np.sum(targets * np.log(probs), axis=1)) return -np.mean(np.sum(targets * np.log(probs), axis=1))
@ -168,7 +168,7 @@ class CrossEntropySoftmaxError(object):
Returns: Returns:
Gradient of error function with respect to outputs. Gradient of error function with respect to outputs.
""" """
probs = np.exp(outputs) probs = np.exp(outputs - outputs.max(-1)[:, None])
probs /= probs.sum(-1)[:, None] probs /= probs.sum(-1)[:, None]
return (probs - targets) / outputs.shape[0] return (probs - targets) / outputs.shape[0]