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There is python code about Relu backward propagation. and code is like dx=(x>0)*dout, what does x>0 part do? Can anyone explain me this line of code?

arajshree
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user3033705
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    Did you try it in isolation? What did you find out? – jonrsharpe Jun 24 '19 at 21:48
  • Please provide a [mcve]. – Code-Apprentice Jun 24 '19 at 21:48
  • You might compare, say, `(True*3)` and `(False*3)`. That said, since `__gt__()` can return objects of *any* type, in isolation, this question isn't amenable to a canonical answer at all. – Charles Duffy Jun 24 '19 at 21:55
  • Since Python operators can be overloaded, it's impossible to know for certain what the `>` will do without knowing the type of `x`. However, for most sensible implementations, the result of `(x>0)` will be either `True` or `False`, and in a numeric context `True` has a value of one and `False` has a value of zero. – Daniel Pryden Jun 24 '19 at 21:55

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The Relu function is defined as: f(x) = max(0,x) It means if x<=0 then f(x)=0, else f(x)=x.

So if x<=0, dx=0, else dx=dout.

Anubhav Singh
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