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Tensor overview

The Swift for TensorFlow APIs use the Tensor type as the primary means for performing accelerated computation. A Tensor represents a multidimensional array of values, and operations on Tensors are automatically dispatched to available accelerators using one of two backends.

A Tensor is generic about the type of the values it contains. The type of these values must conform to TensorFlowScalar, with common types being Float, Int32, and Bool. For example, to initialize two Float-containing Tensors with some predetermined values, you could do the following:

let tensor1 = Tensor<Float>([0.0, 1.0, 2.0])
let tensor2 = Tensor<Float>([1.5, 2.5, 3.5])

If you had left out the <Float> type parameter, Swift would infer a type of Tensor<Double>. Double is the default type for floating-point literals in Swift. Float values tend to be more common in machine learning calculations, so we're using that here.

Many common operators work on Tensors. For example, to add two of them and obtain the result, you can do the following:

let tensor3 = tensor1 + tensor2

The full list of operations you can perform on a Tensor is available in the API documentation.

_Raw operations

Tensor operations are backed by two different means of working with accelerators, yet they have a unified high-level interface. Under the hood, _Raw operations are defined that either dispatch to _RawXLA or _RawTFEager versions, depending on the backend used for the Tensors in question. These _Raw bindings to TensorFlow or X10 are automatically generated.

Normally, you would not need to interact with _Raw operations directly. Idiomatic Swift interfaces have been constructed on top of these, and that's how you typically will perform Tensor calculations.

However, not all underlying TensorFlow operations have matching Swift interfaces, so you may occasionally need to access _Raw operators in your code. If you need to do so, an interactive tutorial is available to demonstrate how this works.