Nag

NAG is an acronym that can refer to several distinct entities, most notably the Numerical Algorithms Group and its associated software library. The Numerical Algorithms Group (NAG Ltd) is a United Kingdom–based company that develops numerical methods software and distributes the NAG Library, a long-established resource in scientific computing used by researchers and industry practitioners.

NAG Library: The core product is a comprehensive collection of numerical routines for scientific computation. It includes algorithms for linear algebra, numerical integration and differentiation, solving differential and difference equations, optimization and root-finding, interpolation, statistics, random-number generation, and special functions. The library is designed for portability and performance, with implementations in Fortran and C and interfaces to other programming languages. It emphasizes accuracy, robustness, and well-documented, language- and platform-independent behavior.

Usage and impact: The NAG Library is employed to develop or augment software across diverse fields such as engineering, physics, chemistry, finance, and data analysis. NAG Ltd provides licensing, technical support, and consulting services to help organizations integrate the routines into larger applications and to ensure numerical reliability and quality in production software.

Other uses: In addition to the Numerical Algorithms Group, NAG can refer to other organizations, projects, or terms depending on context. Clarifying the domain or field is often necessary to determine the intended meaning of the acronym.