NCalc is a .NET library for parsing and evaluating mathematical expressions, written in C# and targeting .NET Framework 3.5. It uses ANTLR 3.3 to generate a lexer and parser from a custom grammar, producing an abstract syntax tree (AST) of logical expressions. The library supports arithmetic, logical, bitwise, comparison, and ternary operators, as well as built-in functions (Abs, Sin, Round, etc.) and user-defined functions and parameters via event handlers. It also includes expression caching, error detection, and serialization. The codebase is well-structured for its era, with a clear separation between grammar, domain model, and evaluation logic. However, it is explicitly unmaintained and superseded by a newer version (ncalc/ncalc). The project uses outdated dependencies (ANTLR 3.3, .NET 3.5) and includes binary DLLs, making it unsuitable for modern .NET projects without significant migration effort. The primary value is as a historical reference or for understanding expression evaluator design patterns.