RK — Relativistic Kinematics

This package provides a C++ double precision implementation of several basic geometric entities and transformations: points in 3d, directions in 3d (unit vectors), 3-vectors, 4-vectors, rotations, linear transformations, and boosts. The main purpose of the package is representing 4-momenta of relativistic particles and related formulae. The package implementation differs from other kinematic libraries in several important respects: * Careful attention is paid to the numerical aspects of various calculations. For example, the "acos" function is not used to calculate angles between almost collinear vectors because "acos" results in an unacceptable rounding error amplification whenever the magnitude of its argument is close to 1. * Important invariants are not affected by rounding errors. 3-vector length does not change under rotations, 4-vector mass does not change under boosts, a combination of any number of rotations is a rotation. * Efficient implementations are provided