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# input_gate

The descriptor of the input gate, which uses default sigmoid activation.

```
var input_gate: BNNSLSTMGateDescriptor
```

## Discussion

Use C style multidimensional array notation to order the memory pointers as `[` [`num_layers`](/documentation/Accelerate/BNNSLayerParametersLSTM/num_layers) `][num_directions][` [`hidden_size`](/documentation/Accelerate/BNNSLayerParametersLSTM/hidden_size) `][` [`input_size`](/documentation/Accelerate/BNNSLayerParametersLSTM/input_size) `/` [`hidden_size`](/documentation/Accelerate/BNNSLayerParametersLSTM/hidden_size) `]`.

If [`lstm_flags`](/documentation/Accelerate/BNNSLayerParametersLSTM/lstm_flags) includes [`BNNSLayerFlagsLSTMBidirectional`](/documentation/Accelerate/BNNSLayerFlagsLSTMBidirectional), BNNS defines `num_directions` as `2`, or otherwise `1`.

---

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