# Queries regarding Symbolic API in MXNet in Julia

**URL:** <https://discourse.julialang.org/t/queries-regarding-symbolic-api-in-mxnet-in-julia/1753>\
**Category:** Machine Learning\
**Tags:** question, mxnetjl\
**Created:** [January 29, 2017, 9:26am UTC](https://discourse.julialang.org/t/queries-regarding-symbolic-api-in-mxnet-in-julia/1753 "2017-01-29T09:26:36Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![kishoreabhishek](https://avatars.discourse-cdn.com/v4/letter/k/a88e57/32.png) [@kishoreabhishek](https://discourse.julialang.org/u/kishoreabhishek)\
**Post date:** [January 29, 2017, 9:26am UTC](https://discourse.julialang.org/t/queries-regarding-symbolic-api-in-mxnet-in-julia/1753/1 "2017-01-29T09:26:36Z")

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I am struggling to understand the symbolic API nuances of MXNet in Julia. I saw an example in MXNet documentation which has the following line: act1 = mx.Activation(data = fc1, name=:relu1, act\_type=:relu)

Why is act\_type assigned a symbol- :relu. Is :relu a function pointer. If not then where do we assign the value to :relu symbol. Why is data not assigned a symbol. Why is name assigned a symbol rather than a string.

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**Author:** ![vchuravy](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/vchuravy/32/8_2.png) [@vchuravy](https://discourse.julialang.org/u/vchuravy)\
**Post date:** [January 29, 2017, 9:30am UTC](https://discourse.julialang.org/t/queries-regarding-symbolic-api-in-mxnet-in-julia/1753/2 "2017-01-29T09:30:40Z")

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As I mentioned in [https://github.com/dmlc/MXNet.jl/issues/193](https://github.com/dmlc/MXNet.jl/issues/193)

There is a difference between Symbols in Julia which are strings that start with : and are optimised representations of immutable strings and MXNet SymbolicNodes e.g. symbols in the python library.  
We use Julia symbols in the API because they are a bit nicer to work with and we use them mostly to name things.

So the Symbol :relu in your example is used to switch the behaviour of the SymbolicNode mx.Activation.  
data can be either a SymbolicNode or the name for a free input (like :data).

Take a look at [What is Cloud Computing? - Soft Cloud Tech](http://dmlc.ml/MXNet.jl/latest/user-guide/overview/#intermediate-level-interface) which explains in a little bit more detail.