# sigmoid

Apply sigmoid activation

## Syntax

``dlY = sigmoid(dlX)``

## Description

The sigmoid activation operation applies the sigmoid function to the input data.

This operation is equivalent to

`$f\left(x\right)=\frac{1}{1+{e}^{-x}}.$`

Note

This function applies the sigmoid operation to `dlarray` data. If you want to apply sigmoid within a `layerGraph` object or `Layer` array, use the following layer:

example

````dlY = sigmoid(dlX)` computes the sigmoid activation of the input `dlX` by applying the sigmoid transfer function. All values in `dlY` are between `0` and `1`.```

## Examples

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Use the `sigmoid` function to set all values in the input data to a value between `0` and `1`.

Create the input data as a single observation of random values with a height and width of seven and 32 channels.

```height = 7; width = 7; channels = 32; observations = 1; X = randn(height,width,channels,observations); dlX = dlarray(X,'SSCB');```

Compute the sigmoid activation.

`dlY = sigmoid(dlX);`

All values in `dlY` now range between `0` and `1`.

## Input Arguments

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Input data, specified as a `dlarray` with or without dimension labels.

Data Types: `single` | `double`

## Output Arguments

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Sigmoid activations, returned as a `dlarray`. All values in `dlY` are between `0` and `1`. The output `dlY` has the same underlying data type as the input `dlX`.

If the input data `dlX` is a formatted `dlarray`, `dlY` has the same dimension labels as `dlX`. If the input data is not a formatted `dlarray`, `dlY` is an unformatted `dlarray` with the same dimension order as the input data.