:nosearch:

.. _op_ai_onnx_Softmax-1:

Softmax - version 1
===================

This page documents version **1** of operator **Softmax**. See :doc:`Softmax` for the latest version (since version 13).

- **Domain**: ``ai.onnx``
- **Since version**: 1

The operator computes the normalized exponential values for the given input.
Inputs are conceptually coerced to a 2D matrix and Softmax is applied on the
second dimension. The output tensor has the same shape as the input tensor.

**Inputs**

- **input** (*T*): The input tensor that's coerced into a 2D matrix of size (NxD) as described above.

**Outputs**

- **output** (*T*): The output values with the same shape as input tensor (the original size without coercion).

**Attributes**

- **axis** (*int*): Describes the dimension Softmax will be performed on. Negative value means counting dimensions from the back.

**Type Constraints**

- **T**: Constrain input and output types to float tensors.
  Allowed types: tensor(double), tensor(float), tensor(float16).