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openvino/docs/ops/normalization/NormalizeL2_1.md
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# NormalizeL2 {#openvino_docs_ops_normalization_NormalizeL2_1}
@sphinxdirective
**Versioned name**: *NormalizeL2-1*
**Category**: *Normalization*
**Short description**: *NormalizeL2* operation performs L2 normalization on a given input ``data`` along dimensions specified by ``axes`` input.
**Detailed Description**
Each element in the output is the result of dividing the corresponding element of ``data`` input by the result of L2 reduction along dimensions specified by the ``axes`` input:
.. code-block:: cpp
output[i0, i1, ..., iN] = x[i0, i1, ..., iN] / sqrt(eps_mode(sum[j0,..., jN](x[j0, ..., jN]**2), eps))
Where indices ``i0, ..., iN`` run through all valid indices for the ``data`` input and summation ``sum[j0, ..., jN]`` has ``jk = ik`` for those dimensions ``k`` that are not in the set of indices specified by the ``axes`` input of the operation.
``eps_mode`` selects how the reduction value and ``eps`` are combined. It can be ``max`` or ``add`` depending on ``eps_mode`` attribute value.
Particular cases:
1. If ``axes`` is an empty list, then each input element is divided by itself resulting value ``1`` for all non-zero elements.
2. If ``axes`` contains all dimensions of input ``data``, a single L2 reduction value is calculated for the entire input tensor and each input element is divided by that value.
**Attributes**
* *eps*
* **Description**: *eps* is the number applied by *eps_mode* function to the sum of squares to avoid division by zero when normalizing the value.
* **Range of values**: a positive floating-point number
* **Type**: ``float``
* **Required**: *yes*
* *eps_mode*
* **Description**: Specifies how *eps* is combined with the sum of squares to avoid division by zero.
* **Range of values**: ``add`` or ``max``
* **Type**: ``string``
* **Required**: *yes*
**Inputs**
* **1**: ``data`` - A tensor of type *T* and arbitrary shape. **Required.**
* **2**: ``axes`` - Axis indices of ``data`` input tensor, along which L2 reduction is calculated. A scalar or 1D tensor of unique elements and type *T_IND*. The range of elements is ``[-r, r-1]``, where ``r`` is the rank of ``data`` input tensor. **Required.**
**Outputs**
* **1**: The result of *NormalizeL2* function applied to ``data`` input tensor. Normalized tensor of the same type and shape as the data input.
**Types**
* *T*: arbitrary supported floating-point type.
* *T_IND*: any supported integer type.
**Examples**
Example: Normalization over channel dimension for ``NCHW`` layout
.. code-block:: cpp
<layer id="1" type="NormalizeL2" ...>
<data eps="1e-8" eps_mode="add"/>
<input>
<port id="0">
<dim>6</dim>
<dim>12</dim>
<dim>10</dim>
<dim>24</dim>
</port>
<port id="1">
<dim>1</dim> < !-- axes list [1] means normalization over channel dimension -->
</port>
</input>
<output>
<port id="2">
<dim>6</dim>
<dim>12</dim>
<dim>10</dim>
<dim>24</dim>
</port>
</output>
</layer>
Example: Normalization over channel and spatial dimensions for ``NCHW`` layout
.. code-block:: cpp
<layer id="1" type="NormalizeL2" ...>
<data eps="1e-8" eps_mode="add"/>
<input>
<port id="0">
<dim>6</dim>
<dim>12</dim>
<dim>10</dim>
<dim>24</dim>
</port>
<port id="1">
<dim>3</dim> < !-- axes list [1, 2, 3] means normalization over channel and spatial dimensions -->
</port>
</input>
<output>
<port id="2">
<dim>6</dim>
<dim>12</dim>
<dim>10</dim>
<dim>24</dim>
</port>
</output>
</layer>
@endsphinxdirective