# Introduction
This crate brings easy to use, efficient, and highly flexi
Rust programming language. Utilizing Rust's extensive and
types in this crate that implement the trait AD can be tho
f64 or f32 that affords forward mode or backwards mode aut
computation in Rust.
# Key Features
- ad_trait supports reverse mode or forward mode automatic
differentiation implementation can also take advantage of
- The core rust f64 or f32 types also implement the AD tra
trait object as a generic type can handle either standard
tracking automatic differentiation with essentially no ove
- The provided types that implement the AD trait also impl
to operate almost exactly as a standard f64. For example,
`ComplexField` traits, meaning it can be used in any `nalg
# Example
```rust
use ad_trait::AD;
use ad_trait::differentiable_block::DifferentiableBlock;
use ad_trait::differentiable_function::{DifferentiableFunctionTrait, FiniteDifferencing, ForwardAD, ForwardADMulti, ReverseAD};
use ad_trait::forward_ad::adfn::adfn;
use ad_trait::reverse_ad::adr::adr;
#[derive(Clone)]
pub struct Test<T: AD> {
coeff: T
}
impl<T: AD> DifferentiableFunctionTrait<T> for Test<T> {
const NAME: &'static str = "Test";
fn call(&self, inputs: &[T], _freeze: bool) -> Vec<T> {
vec![ self.coeff*inputs[0].sin() + inputs[1].cos() ]
}
fn num_inputs(&self) -> usize {
2
}
fn num_outputs(&self) -> usize {
1
}
}
impl<T: AD> Test<T> {
pub fn to_other_ad_type<T2: AD>(&self) -> Test<T2> {
Test { coeff: self.coeff.to_other_ad_type::<T2>() }
}
}
fn main() {
let inputs = vec![1., 2.];
// Reverse AD //////////////////////////////////////////////////////////////////////////////////
let function_standard = Test { coeff: 2.0 };
let function_derivative = function_standard.to_other_ad_type::<adr>();
let differentiable_block = DifferentiableBlock::new(function_standard, function_derivative, ReverseAD::new());
let (f_res, derivative_res) = differentiable_block.derivative(&inputs);
println!("Reverse AD: ");
println!(" f_res: {}", f_res[0]);
println!(" derivative: {}", derivative_res);
println!("//////////////");
println!();
// Forward AD //////////////////////////////////////////////////////////////////////////////////
let function_standard = Test { coeff: 2.0 };
let function_derivative = function_standard.to_other_ad_type::<adfn<1>>();
let differentiable_block = DifferentiableBlock::new(function_standard, function_derivative, ForwardAD::new());
let (f_res, derivative_res) = differentiable_block.derivative(&inputs);
println!("Forward AD: ");
println!(" f_res: {}", f_res[0]);
println!(" derivative: {}", derivative_res);
println!("//////////////");
println!();
// Forward AD Multi ////////////////////////////////////////////////////////////////////////////
let function_standard = Test { coeff: 2.0 };
let function_derivative = function_standard.to_other_ad_type::<adfn<2>>();
let differentiable_block = DifferentiableBlock::new(function_standard, function_derivative, ForwardADMulti::new());
let (f_res, derivative_res) = differentiable_block.derivative(&inputs);
println!("Forward AD Multi: ");
println!(" f_res: {}", f_res[0]);
println!(" derivative: {}", derivative_res);
println!("//////////////");
println!();
// Finite Differencing /////////////////////////////////////////////////////////////////////////
let function_standard = Test { coeff: 2.0 };
let function_derivative = function_standard.clone();
let differentiable_block = DifferentiableBlock::new(function_standard, function_derivative, FiniteDifferencing::new());
let (f_res, derivative_res) = differentiable_block.derivative(&inputs);
println!("Finite Differencing: ");
println!(" f_res: {}", f_res[0]);
println!(" derivative: {}", derivative_res);
println!("//////////////");
println!();
}
```
# Citation
For more information about our work, refer to our paper:
https://arxiv.org/abs/2504.15976
If you use this crate in your research, please cite:
```text
@article{liang2025ad,
title={ad-trait: A Fast and Flexible Automatic Different
author={Liang, Chen and Wang, Qian and Xu, Andy and Raki
journal={arXiv preprint arXiv:2504.15976},
year={2025}
}
```