Crate aegir 

Strongly-typed, compile-time autodifferentiation in Rust.

aegir is an experimental autodifferentiation framework designed to leverage the powerful type-system in Rust and avoid runtime as much as humanly possible. The approach taken resembles that of expression templates, as commonly used in linear-algebra libraries written in C++, and indeed mirrors (in many ways) the concept of Iterator in std.

A key distinction of aegir from existing autodiff frameworks is that it does not rely on a monolithic Tensor type that handles shape transformations at runtime. This would be equivalent to using the ndarray crate to handle all numerical computations and data-storage/layouts. While this has its advantages - like simplicity and ease of use - our approach is a strict generalisation and allows for much greater flexibility. By incorporating both dynamic and fixed-size data structures, we also have the advantage of the various compile-time optimisations that come from using arrays, tuples, and scalars.

Key Features

• Built-in arithmetic, linear-algebraic, trigonometric and special operators.
• Infinitely differentiable: Jacobian, Hessian, etc…
• Decoupled/generic tensor type.
• Monadic runtime optimisation.
• Custom DSL for operator expansion.

Modules

buffers

Module for tensor abstractions and their implementations.

errors

Module for helper error types.

fmt

Module containing formatting logic.

ids

Quality-of-life shortcuts for commonly-used identifiers.

meta

Module containing meta operators.

ops

Module for concrete operator implementations.

Macros

ctx

Helper macro for creating anonymous Context types.

ctx_type

Helper macro for defining simple, auto-magical Context types.

dual

Helper macro to construct a Dual variable.

Structs

Dual

Dual variable for forward-mode autodifferentiation over aegir buffers.

Traits

Contains

Trait for operator Nodes that can assert their symbolic contents.

Context

Trait for types that store data buffers.

Differentiable

Trait for operator Nodes with a well-defined adjoint.

Function

Trait for operator Nodes that can be evaluated against a Context.

Identifier

Interface for type-level identifiers.

Node

Base trait for operator nodes.

Read

Trait for reading entries out of a Context.

Type Aliases

AdjointOf

Alias for the adjoint of a function.

AegirResult

Alias for the result type associated with a function.

DualOf

Alias for the dual associated with a function.

ErrorOf

Alias for the error type associated with a function.

ValueOf

Alias for the value type associated with a function.