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.. _op_ai_onnx_Size-1:

Size - version 1
================

This page documents version **1** of operator **Size**. See :doc:`Size` for the latest version (since version 25).

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

Takes a tensor as input and outputs a int64 scalar that equals to the total number of elements of the input tensor.

**Inputs**

- **data** (*T*): An input tensor.

**Outputs**

- **size** (*T1*): Total number of elements of the input tensor

**Type Constraints**

- **T**: Input tensor can be of arbitrary type.
  Allowed types: tensor(bool), tensor(complex128), tensor(complex64), tensor(double), tensor(float), tensor(float16), tensor(int16), tensor(int32), tensor(int64), tensor(int8), tensor(string), tensor(uint16), tensor(uint32), tensor(uint64), tensor(uint8).
- **T1**: Constrain output to int64 tensor, which should be a scalar though.
  Allowed types: tensor(int64).