Crate formulac 

formulac

formulac is a Rust library for parsing and evaluating mathematical expressions with support for complex numbers and extensible user-defined functions.

Overview

• Parse and evaluate expressions containing real and imaginary numbers.
• Use built-in operators, constants, and mathematical functions.
• Register your own constants and functions.
• Compile expressions into callable closures for repeated evaluation without re-parsing.

Internally, expressions are first tokenized into lexeme, then converted to an AST using the Shunting-Yard algorithm, and finally compiled into Reverse Polish Notation (RPN) stack operations for fast repeated execution.

Feature Highlights

• Complex number support using num_complex::Complex<f64>
• User-defined functions and constants
• Variables and arguments
• Operator precedence and parentheses handling
• Efficient compiled closures avoiding repeated parsing

Example

use num_complex::Complex;
use formulac::Builder;

let expr = Builder::new("sin(z) + a * cos(z)", ["z"])
    .with_constants([("a", Complex::new(3.0, 2.0))])
    .compile()
    .expect("Failed to compile formula");

let result = expr([Complex::new(1.0, 2.0)]);
println!("Result = {}", result);

Example: Retrieving All Names

use formulac::constants::Constants;
use formulac::operators::OperatorKind;
use formulac::functions::FunctionKind;


// Constants
let constant_names = Constants::<f64>::symbols();
println!("Constants: {:?}", constant_names);

// Unary / Binary operators
let unary_names = OperatorKind::symbols();
println!("Operators: {:?}", unary_names);

// Functions
let function_names = FunctionKind::symbols();
println!("Functions: {:?}", function_names);

When to Use

Use formulac when you need:

• Fast repeated evaluation of mathematical formulas
• Complex number support in expressions
• Runtime extensibility via custom functions or constants

License

Licensed under either MIT or Apache-2.0 at your option.

Modules

builder

builder.rs

constants

constants.rs

core

core.rs

err

err.rs

functions

functions.rs

lexer

lexer.rs

operators

operators.rs

Type Aliases

Builder

UserFn