nanograd

Minimal automatic-differentiation engine written in Rust.

Quick start

cargo run --release

Running the demo trains a tiny Multi-Layer Perceptron to learn the XOR function and writes a rendered computation graph of a single Perceptron to graph.html.

Usage

use nanograd::scalar::{Scalar, func};

let x = Scalar::new_grad(2.0);
let y = Scalar::new_grad(-1.0);

// z = relu(x * y + 3)
let z = func::relu(x.clone() * y.clone() + 3.0);
z.backward();

println!("z = {}", z.get_value());
println!("dz/dx = {:?}", x.get_grad());
println!("dz/dy = {:?}", y.get_grad());

How it works

• Each Scalar stores value, optional gradient, and an Edge describing the operation that produced it.
• Operator overloads (+, *, -, ...) and helpers in scalar::func build a directed acyclic graph of Scalars while caching the local derivative for every edge.
• backward() starts at an output node and recursively propagates gradients along the graph, accumulating them into the leaf nodes created with Scalar::new_grad.
• The graph can be visualised with plot::dump_graph, which emits a self-contained D3.js HTML file.