openvino/docs/ops/activation/GELU_7.md

GELU

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.. meta:: :description: Learn about Gelu-7 - an element-wise, activation operation, which can be performed on a single tensor in OpenVINO.

Versioned name: Gelu-7

Category: Activation function

Short description: Gaussian error linear unit element-wise activation function.

Detailed description:

Gelu operation is introduced in this article <https://arxiv.org/abs/1606.08415>__. It performs element-wise activation function on a given input tensor, based on the following mathematical formula:

.. math::

Gelu(x) = x\cdot\Phi(x)

where Φ(x) is the Cumulative Distribution Function for Gaussian Distribution.

The Gelu function may be approximated in two different ways based on approximation_mode attribute.

For erf approximation mode, Gelu function is represented as:

.. math::

Gelu(x) = x\cdot\Phi(x) = x\cdot\frac{1}{2}\cdot\left[1 + erf\frac{x}{\sqrt{2}}\right]

For tanh approximation mode, Gelu function is represented as:

.. math::

Gelu(x) \approx x\cdot\frac{1}{2}\cdot \left(1 + \tanh\left[\sqrt{\frac{2}{\pi}} \cdot (x + 0.044715 \cdot x^3)\right]\right)

Attributes

• approximation_mode

  • Description: Specifies the formulae to calculate the Gelu function.

  • Range of values:

    • erf - calculate output using the Gauss error function
    • tanh - calculate output using tanh approximation

  • Type: string

  • Default value: erf

  • Required: no

Inputs:

• 1: A tensor of type T and arbitrary shape. Required.

Outputs:

• 1: The result of element-wise Gelu function applied to the input tensor. A tensor of type T and the same shape as input tensor.

Types

• T: arbitrary supported floating-point type.

Examples

Example: tanh approximation mode

.. code-block:: xml :force:

<layer ... type="Gelu"> 1 128 1 128

Example: erf approximation mode

.. code-block:: xml :force:

<layer ... type="Gelu"> 3 7 9 3 7 9

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